Hi Mike, the breaker I purchased was a “GET SHUPA 25A 30MA RCD CAT. NO 25R30 RCCB 2 POLE“ £35.99
Ive also just done a quick ebay search and several alternatives came up but not that specific manufacturer. The seller was :-
NIJOLE ASTROMSKIENE
2H Hyde Park Mansions,
Chapel Street,
Marylebone,
London
NW1 5BL
Unfortunately no contact details on receipt other than the address. You might get something very similar from your local electrical supplier.