Zara Phillips has will not be defending her title at the World Equestrian Games

Toytown's career has been plagued with athletic injuries and although he won European and world titles in 2005 and 2006, he missed selection for the 2004 and 2008 Olympic games.

“He's in light work but it is hard to keep him with four good legs so Kentucky is not in his plan, ” said Phillips. “He might do a small competition later this year, but he owes me nothing.

“If you asked me right now if I might be selected to take another horse I'd have to say the odds are long. There are some very good riders and horses already in contention. But a good result at Badminton could change that, who knows?”

Phillips's principal contenders at four-star level have their first outing of the year at Tweseldown, Hampshire, on Thursday. These are Glenbuck, who completed Burghley last autumn, and new ride Poilu, a former racehorse who was fifth at Burghley last year when ridden by the Australian world silver medallist Clayton Fredericks.

Describing 2009 as a “transitional year,” Zara is now concentrating on producing her younger team of event horses for London 2012.