The London Welsh dairies diversified from milk deliveries to found little general stores, and so effectively invented today's corner shop. This one has evolved into a cafe and it's only natural that it should sell bagels, adding in some of the East End's Jewish heritage.
This East End Jewish-Welsh mix always seems an unlikely one to me - despite the fact that I happen to be Welsh with a bit of East End Jewish thrown in. It works very well at Jones Dairy Cafe. (As does the cast iron stove, about 5' tall and articulated so it looks like some rusty-red ancient ziggurat).