The more I look at this image the more I love it. Dated from the children's estimated ages as c. 1895, it strikes me as being quite unusually relaxed for the era, and of exceptional quality.
There is no indication of studio, but on the reverse a hand written caption states: "at 20 Cambalt Road, Putney. H F Tomalin, Mrs Tomalin [Klara], Mr Tomalin [Lewis], Marie Tomalin & Maggie Tomalin".
This is part of a large archive of Tomalin family images I acquired and am slowly starting to sort. Images date from c. 1860s to 1970s. Many are named, particularly the early ones. Lewis here founded the clothing company Jaeger I think about 10 years before this was taken. It was a very notable family, with several notable writers and most recently Thomas Heatherwick (I believe Lewis's great grandson) designing the amazing Olympic Flame for London 2012.