Ellie Simmonds ended London 2012 with four medals after claiming silver in the S6 100 metres freestyle - but the team fell one short of their target as the swimming came to an end after 10 days at the Aquatics Centre.
Simmonds was second behind Victoria Arlen, with the American lowering her own world record, to add silver to the two golds and one bronze she had already won, with Natalie Jones in seventh.
Harriet Lee added the SB9 100m breaststroke bronze to the world title she won in 2010 but with only three visits to the podium over the last two sessions, it meant the team finished with 39 medals, one short of the target set by UK Sport.
Saturday's evening session also saw Jack Bridge finish fourth in the SB9 100m breaststroke, the men's medley relay were fifth in a new British record in the very last aquatics event of London 2012 as was Anthony Stephens in the S5 100m freestyle and Matthew Whorwood was seventh in the S6 100m freestyle.
Simmonds, 17, had already won gold in the S6 400m freestyle and 200m individual medley - both in worl-record time - as well as bronze in the 50m freestyle.
Topping the podium was always going to be tough ask given Arlen's form leading into London.
The American was second in the 400m but in the morning issued an ominous warning when she equalled her world mark.
A few hours later her victory was never in doubt as she led from start to finish to lower her record by 1.41 seconds to 1min 13.33secs.
Simmonds was fourth at halfway before moving through the field to touch well clear in second in 1:14.82, more than two seconds ahead of Tanja Groepper in third.
Her competitive instinct led Simmonds to rue the fact she had not got gold but she was realistic given her opposition in Arlen and her preference for the longer races.
Simmonds said: "Silver is really good. I went out there and did the best I could, I went a PB by over a second.
"I would have loved to have got that gold but you can't have everything your own way.
"You've always got to believe in yourself.
"I believed in myself before the race and my coach Billy (Pye) believed in me as well.
"She pushed me to my limits and I think my limit is 1:14 at this point in time.
"I've been PBing every time I swim so I can't ask for any more."
The Swansea-based swimmer also confirmed her intention to compete in 2016 although she knows fate could intervene.
"I'd love to go to Rio. I'll definitely be going to the next Games, I love the Paralympics, they are amazing.
"You've got to take every year as it comes. You never know with injuries, what happens in my life and my future, my school and stuff.
"I am going to see how every year goes at the moment."
While Simmonds has isolated herself from social media, she is excited, rather than overwhelmed, by the opportunities that are bound to come her way.
For now, though, she wants to spend time at the athletes' village and, watch the closing ceremony and celebrate her achievements - something she has already done once with a McDonald's.
Simmonds is not expecting more accolades, like the MBE she was awarded after her double gold in Beijing, and neither is she looking to emulate the likes of multi-medallists Baroness Tanni Grey-Thompson and Sarah Storey.
She said: "I set my own goals, I go out there and swim the best I can and I am just going to take every year as it comes.
"I am not really thinking 'oh, I am going to get 11 golds' because that is not the case.
"I've got four gold medals which is incredible for me."
Of her rivalry with Arlen, Simmonds hopes it will be long-term, saying: "We are both the same age and I hope it goes on for a long time because it is pushing me to the best of my ability and it is pushing her as well.
"So I think we are going to have a great rivalry.
Hopefully she'll go to Rio and I'll go to Rio and World Champs next year in Canada - we'll push each other on."
Arlen echoed her sentiments, adding: "Me and her are really good friends.
We always wish each other luck. She and I are going to keep going at it. It has been a rollercoaster ride especially after the last few months."
Lee produced a determined finish to touch in third in the SB9 100m breaststroke in 1:19.53.
Lee admitted reaching the podium on her Paralympic debut was the perfect end to a rollercoaster year.
"It's been a hard slog to get here and to finish the whole year of with a medal is quite emotional,'' she said.
"Four months ago I wasn't meant to be here, I wasn't meant to be walking let alone swimming so to be able to get here and get away with a medal is an amazing feeling.
"After being in intensive care, I was told I wouldn't make it here so I wanted to prove everyone wrong and show everyone that I could get here and that I'm made of harder stuff than they seemed to think I was.''
The medley quartet (34 points) of James Crisp, Jack Bridge, Sean Fraser and Thomas Young were fifth in 4:20.54 as China won in a world record of 4:09.04.