Yes the Pension Scheme Trustees must register for VAT and can reclaim the VAT charged (NOT THE PENSION FUND ITSELF).
It will be registered as Mr X (and any other trustees) and the Y Pension Fund. The fund is registered under section 46 of the VAT Act 1994 and Regulation 8 of the Value Added Tax Regulations 1995. This means that all the trustees are jointly and severally responsible for anything done under the VAT Act by the other trustees. There is a separate registration for the activities of the trustee and non-trustee activities. If, however, these are not distinguishable they will have just one registration (for instance if the sponsoring employer is the sole trustee).
HMRC will want the names and addresses and signatures of all the trustees. HMRC cannot make the trustees sign a VAT 2 as this is a form solely for partnerships, but it is often used as a matter of convenience. HMRC may also ask for other independent verification of who the trustees are (e.g. sight of the Trust Deed) to ensure the correct ‘person’ is being registered. As the trustees are jointly responsible for each other’s actions it is possible for one trustee to sign and submit the VAT 1. HMRC would then need to verify the names and addresses of the trustees at a later date.