Peter Burke wrote:

Andy Burns wrote:

you can cap-off the faulty valve, e.g.
https://www.screwfix.com/p/bsp-blank-nut-x/39553

I don't think these are supplied with a sealing washer

They do come with a rubber disc, rather than a washer

so these will be needed too:
https://www.screwfix.com/p/washer/6039j

No harm having some spare washers around though.