The integrity of the BBC was compromised by allowing Robinsons, the fruit squash maker, to sponsor the Sports Personality of the Year programme, the corporation’s regulator concluded today.

A damning ruling from the BBC Trust said that the £200,000 two-year deal with Britvic, the owner of Robinsons, created the misleading impression that the programme had been paid-for by an advertiser — when commercials are banned on the BBC.

“UK audiences expect to receive BBC programmes that are free of advertising and wholly impartial,” the BBC Trust said, after an enquiry that followed complaints from ITV and the Radio Centre, the body that represents commercial radio broadcasters.

As a result of the ruling, the BBC said that all future sponsorship deals will now be scrapped. Last year, the BBC generated £955,000 from advertisers in such sponsorship deals, receiving cash from companies that also included the banks HSBC and National Savings & Investments, and the insurer Aviva.

The finding capped a testing day for broadcasters, after Channel 4 was criticised for breaching impartiality rules, as expected, in its programme The Great Global Warming Swindle. Ofcom confirmed that the fifth part of the programme was biased in favour of critics of the global warming thesis, and that the former chief scientist Sir David King was not treated fairly because his views were misrepresented.

Channel 4 will be obliged to transmit a summary of the ruling but no further sanction will be applied, and the broadcaster said that Ofcom was not able to find that the programme materially misled the audience.

Hamish Mykura, head of documentaries, said: “Ofcom's ruling explicitly recognises Channel 4's right to show the programme and the paramount importance of broadcasters being able to challenge orthodoxies and explore controversial subject matter.”

On sponsorship, the BBC had taken advantage of a loophole that also allows it to mention the names of sponsors of sporting events. It was able to take cash from advertisers for sponsoring what it described as events rather than programmes, which included the Proms in the Park and Young Musician of the Year.

Because Sports Personality of the Year had been transformed into a live event, where members of the public attended, it was able to attract a backer. Held at the Birmingham NEC, with 8,000 in the studio audience, the event was won by Welsh boxer Joe Calzaghe. It was watched by 8.6 million viewers on BBC One.

The BBC Trust concluded that last year’s Sports Personality of the Year “compromised the editorial integrity of the BBC by giving the impression that [via a programme] part of a BBC service had been sponsored”. Specifically, it complained that the Robinson’s logo was too prominently displayed to viewers on the programme set, and that the number of mentions of the brand — four on BBC One, three on Radio 5 Live — was “not editorially justified”.

Technically, the BBC Trust did not say that programme sponsorship was wrong, although it did say that it should “not be a common occurrence”. However, Mark Thompson, the Director-General, is understood to have concluded that it didn’t feel appropriate to continue with it at a time when commercial broadcasters are suffering from a downturn in advertising.

Mr Thompson will now have to personally write an apology to Michael Grade, the chairman of ITV who was previously his former boss at the BBC. ITV said that it was “delighted that our complaint has been upheld” amid what it had described as unfair competition for advertising revenues.

Opposition politicians were also critical. Jeremy Hunt, the Conservative Shadow Culture Secretary, said: “This is a slap in the face for the BBC, and rightly so. When commercial broadcasters are fighting to keep their heads above water, the BBC should know better than to pile on the misery by sucking in sponsorship money through the back door.”

The BBC will continue to provide on-air credits to companies who make large donations to Children in Need and Comic Relief, although it is unclear if partners in the fundraisings will be provided guaranteed mentions. Previously they had been promised explicit on-air mentions in return for the funding.

Despite the verdict and decision, the Robinsons agreement has been allowed to continue, because the BBC struck a two-year deal with the drinks maker, which does not expire until 2009. A spokeswoman for Britvic said it would discuss the ruling with the BBC before taking the matter further.

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