Lock on toilet water tank Bailey Senator 2006

DrDerbyshire

Hi all, thank you for letting me join the forum. I have a Bailey Senator vermont 2006. I need to replace the lock on the toilet flush tank. The part number is 28172. The problem is that the key barrel seems to have become detached and falls out unless I am careful.   I appreciate this is an old caravan now but can anyone recommend where to source this part from please?