Petrus, on whom Philip Robinson put up 2lb overweight, quickened to lead two furlongs out and beat the odds-on Teofilio, who again spoilt his chance by edging left, by two lengths.
Brittain said: "If you are up there Stanley, thank you, and if you are down there Stanley, thank you anyway. Wherever you are I am sure you gave him a shout and this will have given you a great thrill."
Threadwell, who sold Jupiter Island back to his breeder Lady Tavistock prior to his victory in the Japan Cup in 1986, rode 27 winners as an apprentice before turning to a successful career in amusement arcade ventures.
Brittain said: "Stanley was a very good friend. He died a couple of years ago and when I found they were putting a race on in his memory I really wanted to have a runner. I've only got two seven furlong horses that I could have run in this, and this was the one. But I don't like running them when they carry overweight, but today I felt that we were going to get some extra help. I'm sure Stanley would have been giving us an extra kick."
Petrus and another horse became Brittain's property when a sales order was not honoured by a prospective owner and the trainer recalled: "I think this pair set me back about a quarter of a million. That's the pension gone. I think this one is going to be a nice horse for seven furlongs and a mile. He could be a horse for the Hong Kong Bowl next year."
The Tatling won the Joe Pasquale Summer Season Maiden Stakes, being switched inside by Kieren Fallon to head Emerald Peace entering the final furlong and score by one and three quarter lengths.Reuse content