Can https://travel.stackexchange.com/q/79991/47623 please be reopened? Reasons:
My grandparents are travelling to London and ask this as travellers.
This question affects travellers. The City of Westminster's library discusses guests and visitors:
Short stay membership
If you are living in short-term accommodation, you can apply for either short stay membership or a visitor's subscription membership.
If you are visiting Westminster and unable to provide proof of a UK address, you can join as a guest member. You can use our computers and online resources free of charge for one month but you will be unable to borrow books. You will need to provide proof of identity eg a passport, identity card, etc.