The organiser of an event marking the beginnning of the First World War was mugged as he thanked guests for their support.
Tommy Anderson, 58, of Southcote Road in Walthamstow, arranged Sunday's event in Walthamstow Market, alongside the community group, St James St Big Local.
It was attended by about 150 people, including Waltham Forest mayor, Terry Wheeler, and ran from 1pm to 3pm.
Mr Anderson, a former Lance Corporal, arranged a performance by the Caledonian Stow Pipe Band, presentations by the Walthamstow and Chingford branches of the Royal British Legion (RBL), and a blessing by Father Steven Saxby, of St Barnabas Parish Church in Walthamstow.
But during a later tea party Mr Anderson was robbed of £400 by a thief who had sat and watched the service.
He said: "I was standing at the table talking to guests and this man came over to me and said 'what's this all about?'.
" I told him 'you know what this is all about, you've been sitting over there for half an hour'.
"I then felt his hand inside my pocket and he then ran off. I shouted out ‘he's got my money'.
"Two or three people gave chase, but he got into a car in Pretoria Avenue and it drove off."
The 58-year-old, who has worked with various voluntary organisations including Christian Kitchen in Mission Grove and Crest charity shop in High Street, had drawn out the money at an ATM machine earlier that day to buy food and pay his rent and council tax immediately after the event.
Shocked by the turn of events, the community rallied together and had a whip round, raising £130.
The mugger who was dressed in all black clothing, is described as 5ft 2' tall, of a very slim build, has dark hair and olive skin.
For more on this story, see this week's Waltham Forest Guardian - out tomorrow