Thank you both for the info.
This hand detachability lark has its humorous side. The usual explanation is that of the dearth of capable gunsmiths in the far flung corners of the British empire. Therefore they made the locks easily removable for inspection and service.
The local gunsmiths were not to be trusted with unscrewing one or two lock pins for lock removal. Considering that no such provision for quick detachability is made for other bits, like triggers, ribs, stocks, I assume that the gunmakers implied that the locals could be trusted with these parts. There is a dose of British humour there, perceptible to those of us who went through the British education system.