More than £100,000 is needed to safeguard the Derby’s future — the winner last year received £35,000.
In October, Carpetright announced it was ending its sponsorship after two years.
But Lizzie said: “We start printing the schedules from March onwards, so it’s vital we have a sponsor by then.
“The prize-fund for the past few years has been £120,000 and, to maintain the prize-money levels, the sponsorship must cover this.
“With just six months to go, the pressure is on to find a new title sponsor to ensure that this most famous and historic class can continue.”
Tim Stockdale told H&H it would be “a tragedy” if the Derby was lost.
And the future of Britain’s Nations Cup — also held at Hickstead — is also being discussed.
In November, horse sports’ global governing body the FEI announced a new-look Nations Cup series, with a four-year sponsorship package worth €16million from the Saudi Equestrian Fund.
Although Hickstead was told it could still host one of the Nations Cup legs, Lizzie Bunn said at the time the arrangements were still being fine-tuned and it now appears the Saudi sponsorship may not extend as far as first hoped.
The FEI last week told H&H that the new Saudi sponsorship deal will fund the final and contribute towards each qualifier, but the amount varies according to the level of the show. The contribution is thought to be around €50,000 for afive-star such as Hickstead.
Since Europe’s Nations Cup shows are obliged to offer prize-funds totalling €200,000, there remains a sizeable deficit for shows like Hickstead and Aachen to find.
There is also the problem that top riders may divert to the lucrative Global Champions Tour instead, one leg of which next year looks set to clash directly with the Nations Cup at Aachen.
“The organisers of the former Top League and the European Equestrian Federation insisted onhaving €200,000 prize-money at Europe’s leading shows, even when they were aware that the contribution from the sponsor was not going to cover this amount,” said an FEI spokesman.
British Showjumping performance manager Rob Hoekstra said it was “premature to speculate” on the future.
This news story was first published in the current issue of H&H (4 January 2013)