The pressure of being Olympic champion and her decision not to use one of the swimming supersuits were the reasons for Rebecca Adlington missing out on a World Championship medal in the 800metres freestyle, the head coach of Britain's swimming team said today.

On the final night of competition in Rome, Liam Tancock won gold in the 50m backstroke to give Britain their seventh medal in the pool and their best ever showing in the championships.

Surprisingly, while that super seven did include a silver medal in the women's 800m, it came from Jo Jackson and not world record holder Adlington, who finished fourth on Saturday.

The 20-year-old was wearing a Speedo LZR costume rather than one of the performance-enhacing 100 per cent polyurethane outfits, which will be banned next year.

And head coach Dennis Pursley believes Adlington's decision not to use one of the controversial costumes was a reason for her falling short in Italy.

He said: "It was not only the pressure of being Olympic gold medallist but the pressure of being the only one in the race without the suit.

"I think she could have probably have handled any one of those but you put the two together and she was carrying a heavy load."

However, Pursley is confident Adlington will be stronger for the experience. He said: "Not only is she a great athlete but also a great person and has tremendous strength of character.

"She'll be back and I think she will turn this into a great positive. She'll use it to help make it better next time around. We haven't seen the best of Becky yet."

There were no regrets for Tancock, though, as he became the only British man to win a medal in the pool when he struck gold last night.

The Loughborough swimmer returned to the pool 24 hours after reclaiming his world record from Randall Bal, and managed to lower it again by 0.04 seconds to 24.04.

The 24-year-old rose in front and was never seriously threatened as he became world champion for the first time.

It was Tancock's fourth World Championship medal after he took bronze in the same event on his senior international long-course debut in 2005. He repeated that third-place finish two years later and also took a bronze over 100m.

Tancock said: "I'm ecstatic. It's my third World Championships and to finally come away with a gold is just fantastic. To be called world champion and world record holder in the same sentence is pretty impressive."

Unlike Adlington, Tancock was wearing one of the controversial costumes - an adidas Hydrofoil.

While glad he wore it this time, Tancock is comfortable with the decision that means he won't be able to use it next year.

He continued: "We've been put into this situation by the governing body, FINA, but we're all in the same boat. We have to get on with it. They put things in front of you and you just have to jump over it.

"It's great news that things are changing I think that 99 per cent of swimmers are happy about it and I'm one of them. In 2009 I was the fastest man in the world.

"In 2010, I want to be the fastest man in the world, in whatever suit it is, no matter what time. It's just an achievement."

Tancock was Britain's only medallist last night, although Hannah Miley was just 0.43sec off a bronze in the 400m individual medley.

She was third with just 50m to go but was overtaken by Olympic champion Stephanie Rice in the closing stages and was just pipped in 4min 32.72.sec

Miley said: "I'm actually elated. It was so much better than I did in Beijing when I was sixth."