A youth charity’s star horse has died after battling a mysterious illness in intensive care.

The Horse Rangers Association (HRA) at Hampton Court is devastated one of its favourite horses has died in the equine hospital at Liphook.

Aries went into intensive care at the beginning of June suffering from grass sickness.

He was last seen in public at the Queen’s jubilee celebrations in Richmond Park, where he led the escort for Her Majesty and performed in the musical ride display.

Aries, a 19-year-old grey gelding, moved to the Horse Rangers in September 2004 when he retired from the Metropolitan Police Authority, after working for seven years on the streets of London.

He was one of the most popular horses at the Royal Mews stables and was used for hacking out, lessons, jumping and teaching.

A spokesman for the charity said: “Aries was a real fighter, having come through a badly broken leg last year.

“To comfort him, while he was in hospital this time, another horse from the yard, Rufus, was taken to Liphook Equine Hospital to stay with him.”

A fundraising effort was launched to pay for the vet bills and HRA director, Jackie Bryans said she was overwhelmed by the generosity and support shown by people moved by the horse’s plight.

She said: “We want to say a sincere thank you to them and our staff and members.”