The Foreign and Commonwealth Office is working hard to reopen its Legalisation Office as soon as possible. The current position may be seen at: https://www.get-document-legalised.service.gov.uk/select-service. This link also includes a letter from the FCO that can be downloaded describing an emergency procedure.
When the Legalisation Office re-opens, capacity will be reduced and to start with documents will need to be submitted by a consular agent. My consular agent will be one of the agents permitted to do this.
Some embassies are currently providing legalisation services, and some have closed. If you have a document that needs urgent legalisation, please let me know and enquiries can be made as to the status of the relevant embassy.