Baxi Bemuda 552 Thermocouple replaced but still no Pilot Light!

I have a Baxi Bemuda 552 which is about as old as Noah's Ark itself. A couple of months ago the pilot light went out for no reason. Relit it again and it stayed on with no problems until last week when it went out again. This time the pilot won't remain lit. I've replaced the thermocouple and cleaned the pilot jet out. But the pilot STILL won't remain lit!!

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