I'm posting these photos in order, partly, to protect them. I feel they're fairly vulnerable to damage, so want to preserve them as best I can.
This photo is either of Reg or Frank (my uncle and father respectively). It was taken at the [J.W.] Gorsuch studio, 48 Junction Rd, Upper Holloway. A note on Flickr.com says: John Willliam Gorsuch was based at 48 Junction Road, Holloway, Islington from 1891 - 1911. He apparently gambled away earnings from studios at horse races around the country.
This is my grandmother, Karolina Brock again - or, as my uncle (or father) has written on the back: Mother (Mrs K.T.Crowl)
Frank and Reg again; probably Frank is the one on the right.
This is Uncle Will, according to the back of the photo. Presumably that means this is the gent with the extravagant name of William Thackeray Brock. The written 'signature' at the bottom says, Wykeham - the studio was The Wykeham Studios Ltd, 165 Victoria Street, SW1, and also at 133 Streatham High Road, SW161, and 67 Balham High Road, SW12. (The link to Wykeham Studios may only be temporary - it goes to a eBay page where someone is selling an old photo also produced by Wykeham.)