It’s every dressage rider’s dream to take a wobbly four-year-old all the way to grand prix.

For Hertfordshire-based Keith Robertson, that dream is “finally” a reality. The first time he saw Boheme Af Sulsted (Bo), the Danish gelding with four white stockings “had a massive lump on his nose and was terrified of everything”, but always had an “amazing canter”.

“He was an adorable character even then,” remembers Keith, 39, who trains with Emile Faurie. At Bo’s first show, a four-year-old class at Hartpury, he qualified directly for the championship at Stoneleigh by coming second to Carl Hester and Nip Tuck.

“I thought I might as well go to the finals, because the young horse classes are run in pairs, so at least there’s another bum to follow.”

But at the nationals, Bo ended up in the arena by himself after the other horse withdrew. The horse wouldn’t settle, and they finished last.

“He went round with his ears in my nostrils, screaming. He kept trying to exit the arena every time I went past the gate,” says Keith.

“We didn’t bother with the five- and six-year-old classes as he was so big that he didn’t fill out for ages. Even though the judges loved him as a four-year-old — he was legs everywhere — we decided not to try to qualify him.”

At a massive 18hh, Bo’s size has meant that the road to grand prix has been a long and slow one.

“Every time we tried to teach him the changes, they were so big that his body couldn’t cope. He finally got a clean change each way at eight, and then in six months he was doing three and four tempis.

Coming up the grades slowly has paid off. This year has been the 12-year-old gelding’s most successful season yet, with top-three placings in the inter II and grand prix classes at multiple Premier League shows.

“The grand prix work suits him,” says Keith. “He finds piaffe and passage easy, but because he’s so big it takes so much energy. Yesterday he had no fuel left – all the energy was killed by the sun,” says Keith of the pair’s sub-par inter II, in which they scored just over 65% under an unseasonably hot September sun.

The friendly giant

Bo may be a sensitive horse in the arena, but at home he is “super chilled”.

He’ll lick you to death. He would love someone to sit in his stable permanently. Unfortunately he’s a bit agoraphobic so he won’t settle in the field, but he’ll hand-graze for hours,” he says.

Keith runs the busy Wild Farm Equestrian in Hertfordshire. Although there is a lot of foot-fall at the yard, Bo only has to hear Keith’s foot-steps and he neighs every time he hears him approaching.

“He’s sensitive but he’s all mouth and trousers — he wouldn’t say boo to a goose. He gives everything in the arena,” adds Keith.

The pair have a rest day today but tomorrow contest the grand prix — from first draw. This won’t be the last time you hear Keith and Bo’s names.

For a full report from the British Dressage national championships — including analysis, comment and insight — pick up a copy of Horse & Hound next Thursday, 22 September.