The Chalice Well's Trust Deed is in the public domain, via the Charity Commission's website, so I have been able to check as to whether the the quote in the book from Patrick Benham, to the effect that the Trust was obliged to retain the building and use it as a hostel, was correct. The Trust Deed was written in 1959 and amended in 1960, 1968 and 1977, so it is difficult to tell. Here is the aims and objects clause of the Trust document, as amended in 1977, in full:
For the benefit or in furtherance of such charitable institutions or charitable foundations and in such manner and in such proportions as the trustees may from time to time determine and in particular and without prejudice to the foregoing for the following charitable purposes:
(a) To preserve in perpetuity the property known as Chalice Well Glastonbury and surrounding lands for the benefit of the nation and with the intention that it may become a place of pilgrimage rest and recreation.
(b) To preserve the said Chalice Well and its surroundings and to beautify them.
(c) To advance religious and spiritual activities and permit persons of all religious denominations to take advantage of such facilities as the Chalice Well Trust can offer.
(d) To advance education in all ways by encouraging the study and enjoyment of sacred drama and poetry, particularly such as may be associated with the said Chalice Well and its surroundings.
So there is no specific mention of the old school building, and technically it is not correct (assuming that the 1977 amendment did not specifically write the school building out of the document, which is possible since the building had recently ceased to exist) to say that 'The document states quite clearly that the obligations of the Trust include the setting up of a hostel and meeting centre, particularly to cater for the needs of young people from Britain and other countries who might wish to visit Glastonbury for spiritual refreshment.'
Nevertheless, if the aims and objects are read in the context of the building still existing, then all this might be implied. It also may be true, as Patrick claimed around the same time, that the building had a conservation order on it. Sadly, it seems that the Chalice Well Trust, rather than helping to arrive at some clarity, would rather that the subject was simply not discussed.