Joe Swift will not be presenting the BBC's RHS Chelsea Flower Show coverage this year after he signed up with DIY/garden centre chain Homebase to design a show garden at the event.
Swift has presented BBC Chelsea coverage for a decade and is a regular Gardeners' World presenter. Homebase had said any issues about Swift designing and presenting could be overcome.
RHS head of shows development Bob Sweet said: "The BBC has introduced policy guidelines on what is acceptable and what is not and it's obviously going to affect one or two presenters."
BBC communications manager Sonia Cooper said: "Each case is looked at separately. Swift won't be presenting because his sponsor is a garden retailer, which is close to what he does.
"With these activities, nothing is the same for one as for the other because they don't have the same contractual arrangements."
She added in a statement: "The BBC has guidelines that ensure editorial integrity and independence from external interests. Each instance is looked at on an individual basis. Swift is a professional garden designer and Chelsea is the pre-eminent show for designers. He has decided to step back, for this year, from his BBC Chelsea role to concentrate on designing. He will continue on Gardeners' World and as an entrant at Chelsea - we will interview him about his garden."
Alan Titchmarsh will lead the evening coverage and Nicki Chapman daytime. Also presenting will be Carol Klein, Rachel de Thame, Christine Walkden, Alys Fowler, James Wong, Tom Hart-Dyke and James Alexander-Sinclair.
The BBC has reached a compromise with show garden designers Chris Beardshaw and Andy Sturgeon, who will join the TV line-up after medals are presented.