Library Hub Discover will find you books in other libraries in the UK (plus Dublin).
Library Hub Discover does not tell you which of the libraries it lists you can access. For this info see:
The British Library subscribes to several databases not accessible via SIA. They contain some excellent art-related content plus much background material. Three of these are only accessible from the British Library's own PCs:
Once you have joined the British Library and set up an online account, the fourth database can be accessed on your own device from any location:
Visit the British Library's electronic resources list to access this. On the British Library's PCs, the same list gives access to the first three databases above.
See the British Library's LGBTQ histories section if researching British art. There is also a guide to relevant archives and manuscripts in the library.
MA students can join Senate House Library, which offers access to these databases, from within the building only:
For other libraries, see:
The Bishopsgate Institute has a library and archive that 'holds one of the most extensive collections on LGBTQ+ history, politics and culture in the UK.' The collection includes books, magazines and archival items.
WorldCat will find you books in other libraries worldwide. Coverage is uneven; e.g. there are some major African cities with no libraries included.
The SIA librarians will help you find books and access libraries anywhere in the world: though please note our knowledge of many countries is limited.