Diego Garcia Military Base and British Indian Ocean Territory Bill — Explanatory Notes: Bill 364 EN 2024-26 (Lords Amendments)

Bill 364-EN 59/1

DIEGO GARCIA MILITARY BASE AND BRITISH INDIAN OCEAN
TERRITORY BILL
EXPLANATORY NOTES ON LORDS
AMENDMENTS
These Explanatory Notes relate to the Lords Amendments to the Diego Garcia Military Base and
British Indian Ocean Territory Bill as brought from the House of Lords on 13 January. These
Explanatory Notes have been prepared by the Foreign, Commonwealth and Development Office in
order to assist the reader of the Bill and the Lords Amendments, and to help inform debate on the
Lords Amendments.. They do not form part of the Bill and have not been endorsed by Parliament.
These Explanatory Notes, like the Lords Amendments themselves, refer to Bill Number 139, the Bill as
first printed for the Lords.
These Explanatory Notes need to be read in conjunction with the Lords Amendments and might best
be read alongside the Bill. They are not, and are not intended to be, a comprehensive description of
the Bill.
Lords Amendment 1 was tabled by Lord Craig of Radley and was opposed by the Government.
Lords Amendments 2, 3 and 6 were tabled by Lord Purvis of Tweed and were opposed by the
Government.
Lords Amendment 4 was tabled in the name of the Minister Baroness Chapman of Darlington.
Lords Amendment 5 was tabled by Lord Callanan and was opposed by the Government.

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These Explanatory Notes relate to the Lords Amendments to the Diego Garcia Military Base and
British Indian Ocean Territory Bill as brought from the House of Lords on 13 January 2026 (Bill 364)

Commentary on Lords amendments
Lords Amendments to Clause 1: Commencement of Treaty and main provisions of
this Act
Lords Amendment 1:
1. Clause 1 of the Bill provides that clauses 3 (dissolution of the British Indian Ocean Territory),
4 (Continued administration of Diego Garcia) and 5 (citizenship of persons connected with the
Territory) come into force on the coming into force of the Treaty.
2. Lords Amendment 1 would add words to clause 1 of the Bill to make commencement of those
clauses subject to an additional condition. That condition is that the Secretary of State has
sought to negotiate an amendment to Article 11 of the Treaty to ensure that the United
Kingdom would cease to make payments to the government of Mauritius in the event that the
use of the Base for military purpose became impossible.
Lords Amendment 2:
3. Lords Amendment 2 would also add words to clause 1 of the Bill to provide a further
condition to the coming into force of clauses 3 to 5. This condition is that conditions set out in
a new clause 2 of the Bill, concerning the holding of a referendum, are met.
Lords Amendment to insert new Clause after Clause 1: Referendum
Lords Amendment 3:
4. Lords Amendment 3 would add a new clause to the Bill requiring that the Secretary of State
must conduct a referendum of the Chagossian community.
5. This referendum must be held within six months of the day on which the Act is passed. It will
be for the Secretary of State to determine how the referendum will be held but does stipulate
it must be in writing. The amendment sets out the question that the Chagossian community
must be asked.
6. The amendment requires the Secretary of State, within 30 days of the result of the referendum,
to lay a statement before both Houses of Parliament explaining how he or she intends to
respond to the referendum outcomes.
7. The amendment defines the “Chagossian community” as those Chagossians identified by the
Secretary of State who will be impacted by the Act.

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These Explanatory Notes relate to the Lords Amendments to the Diego Garcia Military Base and
British Indian Ocean Territory Bill as brought from the House of Lords on 13 January 2026 (Bill 364)

Clause [5]Further provision: Orders in Council
Lords Amendment 4:
8. Lords Amendment 4 would remove words from subsection (3) of clause 5 to provide that all
Orders in Council made using the power conferred by this clause will be subject to the
negative procedure. Without this amendment, the negative procedure applies only where this
power is used to make provision to amend, repeal or revoke any Act of Parliament or
provision made under an Act of Parliament by statutory instrument.
Lords Amendment to insert new Clause after Clause 5: costs of the treaty
Lords Amendment 5:
9. Lords Amendment 5 would insert a new clause into the Bill to require the Secretary of State to
publish a statement setting out the costs of the Treaty. The statement would be required to
include:
a. the total real-terms cost of the payments to be made to Mauritius under the Treaty.
b. the full methodology and justification of the discount mechanism used to calculate
that total cost.
c. the methodologies used by the Office for Budget Responsibility, the Government
Actuary’s Department, and HM Treasury to calculate the total cost of the Treaty.
Lords Amendment to insert new Clause after Clause 5: Parliamentary oversight and
approval of expenditure
Lords Amendment 6:
10. Lords Amendment 6 would insert a new clause into the Bill to provide for Parliamentary
scrutiny of expenditure arising from the Treaty.
11. Subsection (1) would require the Secretary of State, within the first financial year following
the day on which the Act is passed, to lay before the House of Commons an estimate of the
expenditure expected to be incurred by the United Kingdom Government in connection with
the Treaty. This estimate would be required to include, but not be limited to, any payments
made or to be made to, or financial commitments entered into with the Government of the
Republic of Mauritius in accordance with the Treaty, and the costs associated with the
continued administration, maintenance and operation of Diego Garcia.
12. Subsection (2) would require the Secretary of State to lay a further estimate before the House
of Commons in each fifth successive financial year after the first estimate.
13. Subsection (3) would provide that, where expenditure incurred by the Government exceeds
the amounts anticipated in either the initial estimate under subsection (1) or any subsequent

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These Explanatory Notes relate to the Lords Amendments to the Diego Garcia Military Base and
British Indian Ocean Territory Bill as brought from the House of Lords on 13 January 2026 (Bill 364)

estimate under subsection (2), the Secretary of State must lay before the House of Commons a
supplementary estimate for its approval.
14. Subsection (4) would make provision for circumstances in which the Republic of Mauritius is,
in the view of the Secretary of State, not honouring the provisions of the Treaty. If the
Secretary of State presents to the House of Commons a report that this is the case, and that the
United Kingdom has presented a reasoned case to the Joint Commission and the process set
out in Article 14 of the Treaty has been exhausted, the Secretary of State must lay before the
House of Commons a resolution seeking approval to cease payments in connection with the
Treaty.
Financial effects of Lords Amendments

15. Lords Amendment 3 would result in the Secretary of State incurring significant expenditure
to conduct a referendum, which has been estimated would be likely to exceed £500,000. An
exact figure could only be provided once the nature of the referendum has be en determined.
No money resolution has been passed in respect of such expenditure.

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These Explanatory Notes relate to the Lords Amendments to the Diego Garcia Military Base and
British Indian Ocean Territory Bill as brought from the House of Lords on 13 January 2026 (Bill 364)

Diego Garcia Military Base and British Indian Ocean
Territory Bill
EXPLANATORY NOTES ON LORDS AMENDMENTS
These Explanatory Notes relate to the Lords Amendments to the Sentencing Bill as brought from the
House of Lords on 13 January 2026.

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Ordered by the House of Commons to be printed, 13 January 2026
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