Looking for replacement deck filler cap

[tymonk]

Hi. I'm looking for a replacement cap for my diesel deck filler. The little handle on it broke. I made a little key for it which has been working fine, but I'd feel better having a replacement (especially if I lose the key overboard or something). I'd rather not replace the whole fitting if I do not have to. It's potentially quite old. The major thread diameter appears to be around 53.5mm which thread charts tell me might be a 1 3/4 BSP? I can't find a replacement (only finding one from Australia, if 1 3/4 BSP is in fact right). Hoping someone here can point me in the right direction. Some pics attached. Thank you in advance.

 

[Sandy]

Replace the whole thing with one that uses a winch handle, just don't drop the winch handle in the oggin.

 

[KevinV]

Looks an awful lot like this...

Chromed Brass Diesel Deck Filler (52mm / 2" Hose)