Although only available in just over half of UK households, the multichannel stations took a total share of viewing of 27.7 per cent. In contrast, BBC1's total share of viewing fell from 23.9 per cent last year to 22.3 per cent.
In Sky Digital homes, the BBC's performance was markedly worse - the combined audience share of BBC1 and BBC2 fell below the 20 per cent mark.
Jim Marshall, the chairman of the IPA's media futures group, said: "The BBC does seem to have lost its edge of late. Given the internal turmoil, a resurgent ITV and the growth of multichannel, this is not surprising."
The biggest-rating multi-channel programmes were coverage of the Newcastle United versus Arsenal game on Sky Sports 1, Friends on E4 and the Sky Movies' premiere of Harry Potter and the Chamber of Secrets.
James Wildman, the executive sales director of Flextech's sales house, ids, said multichannel always did well at Easter. "On a generic level, Bank Holidays deliver well for multichannel audiences. It's family time and there is a greater propensity for families to watch television together," he said.
Kevin West, the TV buying director at Starcom MediaVest, agreed with Wildman's assessment. "Multichannel television has done bloody well. The increasingly low price of Freeview set-top boxes - they can be bought for as little as £30 now - is continuing to grow multichannel penetration," he said.
But he warned that it was a concern that terrestrial viewers were being lost to non-commercial channels.