Under EU Directive 85/611/EEC, a depository of an  undertaking  for  collective  investment  in  transferable securities (UCITS) must either have its registered office in the same EU country as that of  the undertaking or be established in  the  EU  country  if  its  registered  office  is  in  another  EU country. UK authorised funds, including UCITS, must have a depositary that is established (has a registered office) and has a place of business in the UK. Eligible EEA firms are able to establish a branch in the UK and obtain a permission to carry out depositary services. The incorporation requirement also applies to a trustee, operator and/or manager of a fun, depending on the legal form of the fund.
"243 Authorisation orders [: authorised unit trust schemes].
(1)If, on an application under section [242(1)(a)] in respect of a unit trust scheme, the [FCA]—
(a)is satisfied that the scheme complies with the requirements set out in this section,
(b)is satisfied that the scheme complies with the requirements of the trust scheme rules, and
(c)has been provided with a copy of the trust deed and a certificate signed by a solicitor to the effect that it complies with such of the requirements of this section or those rules as relate to its contents,
the [FCA] may make an order declaring the scheme to be an authorised unit trust scheme. [...]
[(5)The manager and the trustee must each be a body corporate incorporated in the United Kingdom or another EEA State, and the affairs of each must be administered in the country in which it is incorporated.
(5A)The trustee must have a place of business in the United Kingdom, and the manager must have a place of business in the United Kingdom or in another EEA State.]
(6)If the manager is incorporated in another EEA State, the scheme must not be one which satisfies the requirements prescribed for the purposes of section 264.
(7)The manager and the trustee must each be an authorised person and the manager must have permission to act as manager and the trustee must have permission to act as trustee.
[...]
[261D. Authorisation orders [: authorised contractual schemes]
(1)If, on an application under section [261C(1)(a)] in respect of a contractual scheme, the FCA—
(a)is satisfied that the scheme complies with the requirements set out in this section and section 261E,
(b)is satisfied that the scheme complies with the requirements of contractual scheme rules, and
(c)has been provided with a copy of the contractual scheme deed and a certificate signed by a solicitor to the effect that it complies with such of the requirements of this section or those rules as relate to its contents,
the FCA may make an order declaring the scheme to be an authorised contractual scheme. [...]
(5)The operator and the depositary must each be a body corporate incorporated in the United Kingdom or another EEA State, and the affairs of each must be administered in the country in which it is incorporated.
(6)The depositary must have a place of business in the United Kingdom, and the operator must have a place of business in the United Kingdom or in another EEA State.
(7)If the operator is incorporated in another EEA State, the scheme must not be one which satisfies the requirements prescribed for the purposes of section 264.
(8)The operator and the depositary must each be an authorised person, and the operator must have [such permission as may be necessary to act as operator] and the depositary must have permission to act as depositary.
[...]" (Financial Services and Markets Act 2000 (UKPGA 2000 c. 8), as amended by The Money Market Funds Regulations 2018 (S.I. 2018/698), Sections 243 and 261D)
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"Requirements for authorisation
15.—(1) The requirements referred to in regulation 14(1)(a) [and 14(1A)(b)] are as follows.
(2) The company and its instrument of incorporation must comply with the requirements of these regulations and [FCA rules].
(3) The head office of the company must be situated [in England and Wales (or Wales), in Scotland or in Northern Ireland]. [...]
[(6) If the company has only one director, that director must be a body corporate which is an authorised person and which has a Part 4A permission to carry on the regulated activity of managing a UCITS or, as the case may be, managing an AIF.] [...]
(8) The person appointed as the depositary of the company—
(a)must be a body corporate incorporated in the United Kingdom or another EEA State;
(b)must have a place of business in the United Kingdom;
(c)must have its affairs administered in the country in which it is incorporated;
(d)must be an authorised person;
(e)must have permission under Part IV of the Act to act as the depositary of an open-ended investment company [that is a UCITS or, as the case may be, of an open-ended investment company that is an AIF]; and
(f)must be independent of the company and of the persons appointed as directors of the company. [...]" (The Open-Ended Investment Companies Regulations 2001 (SI 2001/1228), as amended by The Money Market Funds Regulations 2018 (S.I. 2018/698), Regulation 15)
Financial Services and Markets Act 2000 (UKPGA 2000 c. 8), as amended by The Money Market Funds Regulations 2018 (S.I. 2018/698), Sections 243 and 261D
The Open-Ended Investment Companies Regulations 2001 (SI 2001/1228), as amended by The Money Market Funds Regulations 2018 (S.I. 2018/698), Regulation 15
Directive 2009/65/EC of the European Parliament and of the Council of 13 July 2009 on the coordination of laws, regulations and administrative provisions relating to undertakings for collective investment in transferable securities (UCITS), Article 23
[<a href="https://www.legislation.gov.uk/ukpga/2000/8/introduction">Act</a>],[<a href="https://www.legislation.gov.uk/uksi/2001/1228/introduction">Reg</a>],[<a href="https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32009L0065">Directive</a>],[<a href="https://www.handbook.fca.org.uk/handbook/COLL/6/6B.html?date=2018-01-03&timeline=True">Other</a>]