Skip to content
CARTIS
← Return to profile

Cartis diligence evidence schedule

Iron Mountain LON-3 London Data Center

PRJ-0954 · Site · Slough, England, United Kingdom

Record last updated Oct 28, 2026

Scope and capacity

LON-3 is the third Iron Mountain building at Slough and remains under construction. Its 25 MW is a future facility boundary; Q2 2026 reporting gives Q1 2027 expected completion, no pre-leased MW and $391.9 million total expected investment. None of those values is represented as operating capacity. Customer utilization, private contract terms and unreported project financing remain outside the verified public record.

Headline: 25 MW Planned critical IT

Numbers refer to their stated physical boundaries and are not added together. Source dates, claim dates and record updates have different meanings. Missing dates and locators are not inferred.

Claims and exhibit sources

Jump to a claim (20)

Location context · LON-3 | Slough | England | GB

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 65738 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Lifecycle status · Construction

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 65739 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Reported capacity · 25 MW

Design · Iron Mountain LON-3 London Data Center (Project)

Claim 65740 · Recorded claim type: Design · Review: Approved · Claim date: Not stated

Headline treatment: Selected headline

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Capacity basis · Iron Mountain publishes 25 MW for the LON-3 facility record boundary.

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 65741 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Location context · LON-3 | Slough | England | GB

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89163 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Lifecycle status · Construction

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89164 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Reported capacity · 25 MW

Planned / design or future potential · Iron Mountain LON-3 London Data Center (Project)

Claim 89165 · Recorded claim type: Design · Review: Approved · Claim date: Not stated

Headline treatment: Separate claim, not added to the headline

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Capacity basis · 25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89166 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Operator or developer · Iron Mountain Data Centers

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89167 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Project location · Slough, England, GB

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89168 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Current lifecycle · Under development

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89169 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Capacity classification · Future potential

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89170 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Capacity basis · 25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89171 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Customer utilization · Not publicly disclosed

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89173 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Source refresh date · 2026-08-29

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89175 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain LON-3 facility profile

    Iron Mountain Data Centers · Document date: Aug 28, 2026 · Primary

    Source reference: SRC-3716 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london/lon-3

Renewable energy matching · Operator states 100% matched renewable energy where applicable

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89176 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain London campus current profile

    Iron Mountain Data Centers · Document date: Aug 29, 2026 · Primary

    Source reference: SRC-4962 · Fact sheet · Recorded authority: Official primary

    Source URL

    https://www.ironmountain.com/data-centers/locations/emea/london

Sec capacity comparison · Q2 2026 leaseable and development schedules reviewed

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89177 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain Q2 2026 supplemental financial information

    Iron Mountain Incorporated / U.S. SEC · Document date: Aug 6, 2026 · Primary

    Source reference: SRC-4963 · Regulatory record · Recorded authority: Official primary

    Source URL

    https://www.sec.gov/Archives/edgar/data/1020569/000102056926000068/q22026srpfinal.htm

Expected completion · Q1 2027

Forecast · Iron Mountain LON-3 London Data Center (Project)

Claim 89178 · Recorded claim type: Forecast · Review: Approved · Claim date: Not stated

  1. Iron Mountain Q2 2026 supplemental financial information

    Iron Mountain Incorporated / U.S. SEC · Document date: Aug 6, 2026 · Primary

    Source reference: SRC-4963 · Regulatory record · Recorded authority: Official primary

    Source URL

    https://www.sec.gov/Archives/edgar/data/1020569/000102056926000068/q22026srpfinal.htm

Preleased percent · 0 percent

Actual · Iron Mountain LON-3 London Data Center (Project)

Claim 89179 · Recorded claim type: Actual · Review: Approved · Claim date: Not stated

  1. Iron Mountain Q2 2026 supplemental financial information

    Iron Mountain Incorporated / U.S. SEC · Document date: Aug 6, 2026 · Primary

    Source reference: SRC-4963 · Regulatory record · Recorded authority: Official primary

    Source URL

    https://www.sec.gov/Archives/edgar/data/1020569/000102056926000068/q22026srpfinal.htm

Total expected investment · $391,900,000

Transaction scope · Iron Mountain LON-3 London Data Center (Project)

Claim 89180 · Recorded claim type: Transaction scope · Review: Approved · Claim date: Not stated

  1. Iron Mountain Q2 2026 supplemental financial information

    Iron Mountain Incorporated / U.S. SEC · Document date: Aug 6, 2026 · Primary

    Source reference: SRC-4963 · Regulatory record · Recorded authority: Official primary

    Source URL

    https://www.sec.gov/Archives/edgar/data/1020569/000102056926000068/q22026srpfinal.htm

Counterparties and capital

Iron Mountain Data Centers · Developer · CMP-1123

Investment commitment

$391,900,000 · Jun 30, 2026

SEC-reported total expected investment for LON-3 future phases; not a debt financing or current facility valuation.

Iron Mountain Data Centers (Borrower)

Sources (1)

Financing record 185; claim-specific source links appear in the exhibit sources where published.

This schedule captures public Cartis research. It is not a title, lien or legal-opinion report. Document page/section locators and claim review timestamps are included only when published; this version has no separate locator or claim-review-time feed.