Updated

By Martyn Herman

LONDON (reuters) - European champion Fran Halsall wore a bright pink swimsuit so her dad could spot her at the British Olympic qualifiers on Thursday but her medal potential was clear for all to see as she blazed to victory in the 100m freestyle.

Halsall, runner-up in the 2009 world championships in Rome in a British record 52.87, produced two powerful lengths of the London 2012 Aquatics Centre pool to lay down an impressive marker for the summer when she will be part of a powerful home team hoping to gain a clutch of gold medals.

"I was a bit disappointed with the time to be honest but having said that I've never been this fast in Britain and it's the fastest I've swam at this time of year," the gregarious 21-year-old told reporters.

"My coach always says I never really turn up until the summer anyway. So hopefully I'll be able to go faster at the Games and now I'm in the team I can just totally focus on that."

Explaining her garish choice of swimwear, Halsall, who also sported turquoise nail varnish, explained: "My dad normally says 'what's wrong with Fran, her stroke's awful'," Halsall, whose boyfriend will be playing for Britain in hockey at the Olympics, joked.

"My mum has to say 'you're looking in the wrong lane Andrew!' So I wore a bright suit so he can see what lane I'm in."

British record holder James Goddard also booked his place in the team in the 200m individual medley although he was beaten into first place by Joseph Roebuck who is also qualified for the 400m individual medley and 200m butterfly.

Goddard, sixth in Beijing in 2008, produced a superb backstroke length but was overtaken in the final freestyle leg by the impressive Roebuck.

American gold medal machine Michael Phelps and world record holder Ryan Lochte are expected to battle for gold in the 200m medley in London but Roebuck said a bronze medal is up for grabs.

The spectacular wave-shaped Aquatics Centre witnessed its first world record when British Paralympian Eleanor Simmonds won the 200m Mixed Class IM in 3:08.14.

The trials end on Saturday when the majority of the British team will be confirmed.

(Editing by Justin Palmer)