Despite appearing to hurt his wrist in the fall, he continued to lap on his Tech 3 Yamaha, but he rarely looked likely to challenge for points and he followed home the field with his head bowed a lap behind Stoner.
"Today has been possibly the most disappointing day of my life," he said. "I have let everyone down.
"The weekend wasn't about personal achievement and letting myself down comes second to letting the fans down.
"There's nobody and nothing to blame other than over-exuberance on the first corner. But when you start from 16th place there are two options. One is to ride around at the back of the pack and the other is to go for it. I did the latter."
Stoner dominated from start to finish all weekend at Donington
Toseland was forced to ride without being able to use the back brake of his Tech 3 Yamaha after smashing the footpeg off his bike, but even though he would be unable to compete, the Briton was determined to finish the race.
"The fans came to see me complete 30 laps and even though I knew I couldn't finish competitively I gave them that."
At the front, Stoner's victory was as comfortable as it was consummate, and he said afterwards: "We weren't really sure this new set-up would work around this circuit but it did and I hope it can continue. At least we can fight for the championship now.
"We have picked it up a little bit this weekend and, with this new setting, and if we can carry on, then maybe we can chase the championship leaders down."
The real race battle occurred between Rossi, in his 200th grand prix, and Pedrosa in the tussle for second.
I am happy because I am back on the podium and it is important to finish in front of Dani Pedrosa
Valentino Rossi
The pair toed and froed throughout the race, until the toil of having to battle through the field from ninth on the grid appeared to take its toll on Pedrosa, who eventually settled for third.
It means Rossi extends his championship lead over the Spaniard, while Stoner leaps into third spot to keep his hopes of retaining his title just about alive.
"We tried for the victory but Casey was too fast," said Rossi. "But I am happy because I am back on the podium and it is important to finish in front of Dani Pedrosa.
"Next time, we have to try harder to go for the win."
Down the field, Colin Edwards earned some valuable points in recovering from a poor start to grab fourth, while Andrea Dovizioso will be delighted to have secured fifth.
Jorge Lorenzo, meanwhile, enjoyed arguably the most impressive race, moving from 17th on the grid to sixth despite only having had a skin graft on his hand just a week ago.
British MotoGP result:
1 C Stoner (Aus) Ducati Marlboro 44 mins 44.982 secs
2 V Rossi (Ita) Fiat Yamaha 44:50.771
3 D Pedrosa (Spa) Repsol Honda 44:53.329
4 C Edwards (US) Tech 3 Yamaha 44:57.660
5 A Dovizioso (Ita) JiR Team Scot 44:59.783
6 J Lorenzo (Spa) Fiat Yamaha 45:00.672
7 N Hayden (US) Respol Honda 45:03.178
8 C Vermeulen (Aus) Rizla Suzuki 45:06.648
9 S Nakano (Jpn) Honda 45:14.336
10 A West (Aus) Kawasaki 45:26.012
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