Hi Darren,
Let's see from where we can try to unravel this ...
Marriage 8 Mar 1903 St Barnabas, South Lambeth
Alfred William Helbrough, 21, Bachelor, Motor Mechanic, 194 Wandsworth Rd, father William Helsbrough (deceased), Piano Forte Maker
Ellen Mary Weaver, 19, Spinster, 194 Wandsworth Rd, Father John Weaver, Boiler Maker
Witnesses T Mc Alister and H McAlister
(your Thomas and Harriet, I suppose)
So Harriet's mum's second husband was John Weaver it seems, and Ellen Mary was born ca. 1884.