Hi guys,

looks like a 4293 to me

Bs 4293.

- - - Updated - - -

FFS. I'll never win anything in life.

Thanks Guys

Hi and welcome

The Wylex WEM80/2 is far too old to comply with a harmonised BS EN standard, they were introduced as Current Operated Earth Leakage Circuit Breakers (COELCB) in the early 1980s, to replace the previous Voltage Operated Earth Leakage Circuit Breakers (VOELCB). The Wylex WEM80/2 was a general purpose RCD (COELCB) manufactured to BS 4293. The old Wylex WES and WEM BS 4293 types were notoriously failure prone. Usually by becoming more sensitive than normal or not being resettable. It used to be a regular little earner replacing those things back in the day.
BS 4293 RCDs are usually the general purpose, stand alone, types that were quite common years ago, but were phased out in the early 1990s. Most commonly found as a front end RCD of TT installation, but only on rare occasions an S (time delay) type as they were very expensive and usually only available to special order direct from the manufacturer.
When testing a BS 4293 general purpose type RCD the testing method is the same as normal. @1/2xIΔn on both + and - phases, the RCD should not trip within 2s. @1xIΔn on both + and - phases the RCD must operate within 200mS (Note this is shorter than the BS EN 61008 RCDs we are familiar with). On 30mA RCDs only, test additionally @5xIΔn on both + and - phases, the RCD should trip within 40ms.
If it's a BS4293 S type (time-delay) RCD the testing method is a little different, first you may need to select the RCD time-delay test mode if your tester has one, and perform @1/2xIΔn on both + and - phases, the RCD should not trip within 2s, as normal. @1xIΔn on both + and - phases, there is a 200ms time-delay and 200ms fault time, the RCD should trip within 50% of the time-delay + 200ms and 100% of the time delay +200ms i.e. between 300-400ms@1xIΔn. Most testers don't allow testing at 5xIΔn in this mode even for 30mA S type RCDs, it is inhibited automatically. The result is not required anyway even if the test is performed.
BS 4293 RCDs have since been replaced by the BS EN 61008 types we are more familiar with.