I'll try ThePartsCentre tomorrow. Lots of firms say they have just one as TPC do, but on checking they do not actually have stock and then they say it's obsolete and no longer available. Hence I'm looking at scrap or secondhand.
My boiler has a continuous leak from this part. The boiler is obsolete and I managed to order the last available spare. Unfortunately, it has gist list in transit. Any suggestions or have a discarded boiler from which a spare may be scavanged?