Thanks to all for sterling detective work. The GWF comes up trumps.
That particular Private Hall was the likeliest on my list of Private Halls. I had wondered if Ernest, the eldest son had been named after his father. Cross checking against my database reveals the following and a very sad coda:
615853 Private Edward Ernest Montague HALL
Born in Hoxton, Resided in Kingsland, N.
He originally enlisted in Hackney as 210395 in 25th Battalion, The Rifle Brigade
Private Hall was Killed in Action with 1/19th Londons on 08/08/1918 and is buried in Heath Cemetery, Harbonnieres (grave VIII. G. 16)
The 1/19th weren't actually in action that day and had been holding a quiet part of the line near Albert. His death is not mentioned - it has either been omitted (not uncommon for an OR), or else he was one of the 2 other ranks wounded in the line near Lavieville on 31st July and in fact died of wounds.
Roll of Honour in 'Memories', 19th London OCA Journal, (1924, Q4)
Medal Rolls, 19th London Regt (BW&VM Rolls p. 610)
War Diary 1/19th London Regt
I wonder what happened to the 5 surviving children? I will scan and post the photos. Its hard to tell the ages, but she is clearly a youngish woman and the photo shows the baby on her knee - 32 would be plausible. The son who was killed could well be 6 in his picture.