Zara Phillips MBE returns to the Isleham One Day Event in a star-studded line-up of more than 500 competitors this weekend.

The Queen’s 33-year-old granddaughter has entered this year’s event at the Whitehall Farm event complex and is set to be joined by several of her GB teammates.

Tina Cook and Nicola Wilson — who partnered Phillips to a team eventing silver medal at the London 2012 Olympics — have also registered for Sunday’s open intermediate event.

Other Team GB riders scheduled to compete include Oliver Townend, Georgina French and Laura Collett, while competitors from the Australia, New Zealand and Sweden teams will also be in the competition.

Phillips will be on her Olympic ride, High Kingdom, as she faces a tough field of riders from all corners of the globe.

The Isleham One Day Event began in 1991 and will once again be the first meeting on the 2015 British eventing calendar.

And joint organiser Jackie Seddon is expecting another strong turnout for the event’s 24th staging, if the weather holds out.

“We’ve been very busy and are really pleased with the line-up,” she said. “We are hoping for a good crowd for the weekend, but it all depends on the weather.

“There has been lots of hard work put into the many trade stands which support the event each year.”

The competition clashes with three other events running across the country in Dorset, Northamptonshire and Yorkshire, but Seddon is confident the Isleham ground will attract healthy numbers after it withstood the recent winter weather.

“Our ground goes most of the time, and riders tend to go for the lighter surface,” said Seddon. “It’s the start of the year so hopefully it will run good.”

The event — which is free to attend — starts on Saturday (8am) with the British Eventing 90 and 100 sections, which will see inexperienced horses take on dressage, show jumping and a cross country.

Sunday (8.30am) features a range of sections, including the open Intermediate for experienced horses competing on a cross country course of 21 numbered fences.