Cos I'm looking for a LN5940 (40A Type 2 MCB) for my old MK 'Sentry' CU and you might still have (a good) one sitting in the bottom of a box somewhere?
I believe you can get an adaptor / conversion kit to allow you to mount a modern (flat front and ending with a 's' rather than the sorta 'sculpted' look I believe) ones but I'd rather use the one that would go straight in?
All the best ..
T i m
p.s. I'd swap it for some drinking vouchers of course ;-)