London 2012: behind the scenes at the GB trials - in pictures

Here's one of the two things that the athletes will be attempting to win at the event. The other is a qualifying place on the Team GB Olympic squad Photograph: Bryn Lennon/Getty Images for Aviva

Martyn Rooney signs in Photograph: Bryn Lennon/Getty Images for Aviva

Mo Farah's coach prepares his jersey ahead of his 1,500m heat. Farah usually races at 5,000m and 10,000m but was concentrating on his speed work Photograph: Bryn Lennon/Getty Images for Aviva

With the label securely fastend to his vest. Mo Farah makes his way to the track for his race Photograph: Bryn Lennon/Getty Images for Aviva

Farah won his heat and progressed to the 1,500m final, though on Saturday morning the 29-year-old pulled out of the final after deciding with his coach Alberto Salazar to focus on defending his European 5,000m title in Helsinki next week Photograph: Bryn Lennon/Getty Images for Aviva

Athletes prepare for their heats Photograph: Bryn Lennon/Getty Images for Aviva

Former 400m runner turned TV presenter Iwan Thomas makes a couple of last minute checks Photograph: Bryn Lennon/Getty Images for Aviva

Mark Lewis-Francis pins his race number to his shirt as he prepares for his 100m heat. He made it through his heat, and his time of 10.32sec meant he lined up in Saturday's final Photograph: Bryn Lennon/Getty Images for Aviva

More preparation in the warm-up area Photograph: Bryn Lennon/Getty Images for Aviva

UKA Officials keep an eye on the finish line Photograph: Bryn Lennon/Getty Images for Aviva

Race numbers await their athletes Photograph: Bryn Lennon/Getty Images for Aviva

Jessica Ennis greets a school relay team Photograph: Bryn Lennon/Getty Images for Aviva

Ennis awaits the start of the day's action Photograph: Bryn Lennon/Getty Images for Aviva

Even big stars have to pin their own number onto their vest Photograph: Bryn Lennon/Getty Images for Aviva

Ennis heads out onto the track Photograph: Bryn Lennon/Getty Images for Aviva

Ennis chats with Phil Jones of the BBC. She was competing in four events - 200m, long jump, high jump and 100m hurdles - as she prepares to battle for heptathlon gold at the Olympics. She was in sensational form winning the high jump with a season's best leap of 1.89m and the 100m hurdles with a time of 12.92sec Photograph: Bryn Lennon/Getty Images for Aviva

Aviva GB Team coaches share a joke Photograph: Bryn Lennon/Getty Images for Aviva

Impressive knitwear on show amongst the fans Photograph: Bryn Lennon/Getty Images for Aviva

Chris Tomlinson warms up ahead of his third place finish in the long jump with a distance of 7.89m Photograph: Bryn Lennon/Getty Images for Aviva

Kit hangs in readiness for selection Photograph: Bryn Lennon/Getty Images for Aviva

Coaches Aston Moore and Linford Christie, right, chat with Team GB Head Coach Charles van Commenee Photograph: Bryn Lennon/Getty Images for Aviva

Equipment behind the scenes Photograph: Bryn Lennon/Getty Images for Aviva

Athletes prepare Photograph: Bryn Lennon/Getty Images for Aviva

It's no wonder Christine Ohuruogu looks happy, she won the 400m in very impressive fashion with a time of 51.89sec Photograph: Bryn Lennon/Getty Images for Aviva

The athletes in the men's 100m final including Dwain Chambers, front, and Harry Aikines Aryeetey, centre, make their way onto the track Photograph: Bryn Lennon/Getty Images for Aviva

Dwain Chambers is congratulated by Mark Lewis-Francis after winning the 100m final with a time of 10.25sec. His victory gives UK Athletics a huge selection headache. Adam Gemili was second – and bagged a spot at the Games Photograph: Bryn Lennon/Getty Images for Aviva