www.bbc.co.uk/news/uk-england-london-59459947
Some sources speculate that it is the jubilee line, some sources speculate that it's the bakerloo line. I admit to being personally invested as DH commutes to canary wharf from north London and uses this line daily; if it closes, he has to get the DLR and you can imagine how crowded that would be as Jubilee line is already packed...