Olympic dreams will be realised and dashed on the Parliament Hill athletics track on Saturday night as Britain’s top 10,000m runners battle it out for seats on the plane to Rio.

Highgate Harriers are hosting their fourth annual Night of the 10,000m PBs event – a meeting that was initially designed to give club runners the best possible chance of beating their personal best over 25 laps of the track.

The event – which is free for spectators – has since gone from strength to strength and, this time, the final two races are acting as the Olympic trials for Great Britain’s long-distance runners.

Team GB can enter three men and three women for the 10,000m in Rio in August, and four of the representatives will be selected in Gospel Oak on Saturday.

The first two British finishers in each of the men’s and women’s races will earn spots in the squad, provided they have achieved the qualifying time – 28 minutes for the men and 32:15 for the women – at this weekend’s event or in a previous race.

Reigning Olympic champion Mo Farah is virtually assured of his place already and is not taking part.

But Andy Vernon, who was second behind Farah when he won silver at the 2014 European Championships, will be in action – and the women’s race will be a star-studded showdown featuring 42-year-old Jo Pavey, who is hoping to compete at a fifth Olympics, and her British rivals Kate Avery and Beth Potter.

Event organiser Ben Pochee, who manages Highgate’s long-distance men’s teams, said: “We’ve made the women’s race this year the headline act because it’s almost the quality of a Diamond League meeting.

“The 2009 world champion Linet Masa is in the race to try to get the Rio qualifying time ahead of the Kenyan trial, which is held at altitude and could well be a slow race.

“She’s in it looking for a quick time and you’ve also got Jo Pavey, the 2014 European champion. She doesn’t have the qualifying time so she too will be pushing the pace because she needs to run sub-32:15.

“Then what makes it interesting is you’ve got two other British women who do have the qualifying time, Kate Avery and Beth Potter. They’re going to be sitting on Jo, not looking for a quick race, not helping her to push the pace on – they’ll be very happy if she doesn’t get the qualifying time –and then trying to outsprint her.

“We’ve also got another host of Olympians and internationals looking for a qualifying time in that women’s race.

“In the men’s race, Andy Vernon already has the qualifying time so all he needs to do, even in a slow race, is to finish first or second.

“It may well be that he’s the only one that gets pre-selected, that gets the time – but if someone else comes first or second and doesn’t get the qualifying time, they’ve still got until July 11 to go elsewhere and try to get it.”

In addition to the Olympic trials, British Athletics will also be using Saturday’s elite races to select their 10,000m runners for July’s European Championships and the European Cup, which will take place in Turkey on June 5.

The men’s qualifying time for the European Championships is 25 seconds slower than the Olympic mark at 28:25, while the time needed to be eligible to compete at the European Cup is 29:40 – the same as the women.

“There’s three Great Britain vests up for grabs this weekend,” said Pochee. “It’s everything we wanted for the event, which was to try to provide the platform for people who are one tier below to take another step up and then maybe next year make a further step up, which is what they’ve never had in this country.

“It’s been fantastic and it seems to have caught everyone’s imagination, from volunteers to the athletes. The fact that people are coming to little Parliament Hill athletics track from Hungary, Kenya, France and Germany, and they’re coming for this volunteer event, is absolutely wonderful.”

The first of Saturday’s six races starts at 5pm, with the elite men’s clash beginning at 8.15pm and the women’s event following at 9pm.

Entry remains free and spectators can get up close to the action, being allowed to stand on the track once again, while drinks will be available and music, circus acts, singers and dancers will supplement the sporting entertainment.

Pochee said: “Where else can you see Olympians and world-famous athletes fight for the Olympic dream 100 per cent free and stand in lane three, inches away? It’s a once-in-a-lifetime opportunity.”