Turner, 32, retiring this year after 763 winners in a 15-year career, had five races on her final day.
She was no higher than fifth in the first four but was pressing for the lead aboard 25-1 shot Buonarroti into the final furlong, on heavy ground.
However, 10-1 Litigant powered through to win by four-and-a-half lengths.
Turner was riding Buonarroti for trainer Declan Carroll, who gave her a first opportunity in the saddle in 2000.
She has one more assignment as a jockey, travelling to South Africa next week for the Jockeys' Challenge.
The Nottinghamshire rider was given a warm reception on her return to the paddock and was full of praise for both her mount and the winning rider.
"I'm delighted for George, he works so hard. He's a heavy chap and he has to really put the effort in," she said.
"The horse ran a blinder. Declan actually really fancied him before the race so he gave me plenty of confidence.
"I did [think I might] win but when George came past me like that, I thought he would do well to hang on for second and he did and kept going. He's run a blinder. There's no tears - I feel all right about it."
It was a second victory for trainer Joe Tuite with Litigant but Baker rode the horse to victory three times under trainer Seamus Durack.
"I know he had top weight but he is a class horse and without doubt he is going to step up and be a Cup horse next year," the jockey enthused.
Hayley Turner, Britain's most successful female jockey, finished second in her final UK race as Litigant won the November Handicap at Doncaster.