Lived at 17 Carlisle Street, Soho Square. Died aged 33. We think it likely that this GMA is the same George Maule Allen mentioned on the Kemble family website as marrying Annie Constance Twiss in 1865, and dying in 1889. If that website has the date of the marriage correct then Annie was 2 and George was 10. We think it likely that the marriage date was not 1865 but 1885. No children are listed so the fountain was probably erected by Annie (who went on to marry again in 1893). Or we could be totally wrong.
2019: Paul Frecker kindly wrote to say: "You're quite right. George Maule Allen married Annie Constance Twiss, daughter of Quintin Twiss, on 3 January 1885 at St Peter's Church, Eaton Square (Source: Pall Mall Gazette, 3 January 1885). The premises at 17 Carlisle Street were in his family, the law firm of Allen and Son, for several generations. Actually, it wasn't his widow who erected the fountain, it was his father." GMA joined his father's law firm in 1884.
We are grateful to Paul for taking the time to share this information.