Any knowledge on ref. 2722 cal. 420 Omega 1956

Hi there,

I’m about to buy a 1956 Omega ref 2722-1SC cal. 420 and have been able to find next to no information about them online - I was hoping somebody here might know something!

Dead Link/roverimp/1/710-53481-19255-0/1?pub=5574889051&toolid=10001&campid=5337239012&mpt=2851313

This is the listing - I got it for £220 which seems a good price but as I can’t find out anything about this type I’ve no idea whether it is. Any help welcome!

Thanks in advance