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Diego Garcia Military Base and British Indian Ocean Territory Bill

Lifecycle: Response Published Foreign, Commonwealth & Development Office · Ministry of Defence Last regenerated 10 hours ago

Summary

What this is

A Government Bill to give effect to, and make provision in connection with, the UK-Mauritius Agreement concerning the Chagos Archipelago — transferring sovereignty over the archipelago to Mauritius while securing a 99-year lease for the UK-US Diego Garcia military base.

Why it matters

The Bill ends a contested British Overseas Territory, implements a treaty laid under CRAG 2010, and locks in operational security at one of the most strategically important US-UK military bases in the Indian Ocean — while raising live questions about Chagossian rights, Pelindaba Treaty compatibility and cost to the public purse.

Current status

The Bill is at Consideration of Commons Reasons stage in the Lords (HL Bill 163 series, January 2026), following Commons rejection of three Lords amendments on financial-privilege grounds; ministers made further statements on 13-14 April 2026 about the state of the treaty and Bill.

What changed recently

  • 13 Apr 2026 — Minister of State Stephen Doughty made a Commons statement responding to speculation about the state of the Diego Garcia treaty and the associated Bill. →
  • 14 Apr 2026 — The 13 April Commons statement was repeated in the Lords. →
  • 26 Jan 2026 — Priti Patel tabled an Urgent Question in the Commons seeking a statement on the Government's plans for the Bill; repeated in the Lords by Baroness Chapman. →
  • 21 Jan 2026 — Bill returned from the Commons to the Lords with one Lords amendment agreed and reasons given for disagreeing to others. →
  • 20 Jan 2026 — Commons considered Lords amendments; Lords amendments 2, 3 and 6 engaged Commons financial privilege and were rejected. →

Key documents

Framework

Operationalising

Scrutiny

Evidence

Commentary

Stakeholders

Grouped by role with evidence. Long groups scroll inside their column.

Sponsoring department 2

  • Foreign, Commonwealth & Development Office → src
    Sponsoring department for the Bill and the UK-Mauritius Agreement; produced the Explanatory Notes, Delegated Powers Memorandum and ECHR Memorandum.
  • Ministry of Defence → src
    Co-lead on operational and security provisions for the Diego Garcia base; Lord Coaker (MoD Minister of State in the Lords) led ministerial correspondence on the Pelindaba Treaty.

Sponsoring minister 4

  • David Lammy ↗
    Commons sponsor of the Bill (then Foreign Secretary); FCDO.
  • Baroness Chapman of Darlington → src
    Lords sponsor and FCDO Minister of State; moved Second Reading on 4 November 2025 and answered the Commons Urgent Question (repeat) in the Lords on 26 January 2026.
  • Lord Coaker → src
    MoD Minister of State in the Lords; signed the 8 January 2026 letter to Baroness Goldie and Lord Lilley on Pelindaba Treaty compatibility.
  • Stephen Doughty → src
    FCDO Minister of State; made the Commons statement on 13 April 2026 on the state of the Diego Garcia treaty and associated Bill.

Shadow minister 2

  • Priti Patel → src
    Conservative, Witham; tabled the 26 January 2026 Urgent Question to the Foreign Secretary on the Government's plans for the Bill.
  • Lord Callanan → src
    Conservative front-bench in the Lords; tabled motions in lieu on inoperability of the Diego Garcia base and on Chagossian rights, return and a Mauritius-funded self-determination referendum (HL Bill 163(c)).

Lead committee 5

  • Lords International Agreements Committee → src
    Published HL Paper 146 (9th Report, 25 June 2025) scrutinising the UK-Mauritius Agreement under CRAG, including SOFA implications.
  • Lords Delegated Powers and Regulatory Reform Committee → src
    Published the 37th Report (13 November 2025) on the Bill's delegated powers and a 43rd follow-up Report (23 December 2025) on the Government response.
  • Lords Constitution Committee → src
    Published the 14th Report (20 November 2025) on the Bill, cited as a relevant document throughout Committee and Report stages.
  • Lords International Relations and Defence Committee → src
    Published the 2nd Report (17 December 2025) on Chagossian views on the UK-Mauritius Chagos Agreement.
  • Commons Foreign Affairs Committee → src
    Took oral evidence on The Chagos Agreement (HC 1097, 23 June 2025), cited as a relevant document for Commons Second Reading on 9 September 2025.

Commentator 3

  • Lord Purvis of Tweed → src
    Liberal Democrats, Lords; tabled motions in lieu requiring an inoperability assessment, an exchange of letters with Mauritius confirming Chagossian legal rights to resettlement/participation/decision-making, and a power to cease Treaty payments where Article 14 has been exhausted (HL Bill 163(c)).
  • Baroness Goldie → src
    Conservative peer; addressee of Lord Coaker's 8 January 2026 letter on the Pelindaba Treaty, having raised the issue at Lords Report stage.
  • Lord Lilley → src
    Conservative peer; copied addressee of Lord Coaker's 8 January 2026 letter on Pelindaba Treaty compatibility.

Open questions & gaps

Known gaps in the evidence base and what's still pending.

Pending in the lifecycle

  • Final disposition of the Lords motions in lieu under HL Bill 163(c) — inoperability assessment, Chagossian rights exchange of letters, and cessation of Treaty payments — following Commons financial-privilege rejection of Lords amendments 2, 3 and 6.
  • Whether the 13-14 April 2026 ministerial statements signal a change in timetable or substance for the Treaty's entry into force and the Bill's remaining stages.
  • Confirmation of the Government's position on a substantive debate and vote on the Treaty itself under the CRAG 2010 process, as raised in PQ 464902 (April 2026).

Beyond the corpus

  • MISSING FCDO Impact Assessment for the Bill and Treaty, as referenced by retrieval phase 0a (not located in the events list). — Standard expectation for a Government Bill of this constitutional significance, and asked about in PQ 521608 on cost to the public purse.
  • MISSING Government Response to the Lords International Agreements Committee 9th Report (HL Paper 146). — Conventional follow-up to CRAG-scrutiny reports; not surfaced in the events list.
  • MISSING Final treaty text laid as a Command Paper with explanatory memorandum under CRAG s.20-25. — Required step under the CRAG 2010 framework; the corpus references the Agreement but a discrete CP number/lay date is not in the events.

Confidence gaps

  • Exact stage of the Bill after the 13-14 April 2026 statements is not clear from the events alone — whether further Lords ping-pong has been scheduled.
  • Status of any UK-US Status of Forces Agreement specifically for Diego Garcia post-transfer is referenced in the IAC report but not in a standalone document on this thread.