BBC Scotland yesterday defended the planned big-budget live broadcast of climbers tackling some of Britain's most formidable rock faces after bad weather led to its cancellation at the weekend.

The BBC may be left facing a large bill after the pioneering show, The Great Climb, was first postponed from Saturday and eventually cancelled yesterday but executive producer David Harron stood by the value and importance of making ambitious programmes.

The broadcast live from the Cairngorms National Park, which had been in the pipeline for a year-and-a-half, was to have been filmed in HD (High Definition) from the perspective of the rock climbers and would have been a world first in television history.

It would have provided viewers with a spectacular mix of physical drama and dramatic scenery with narratives about the local habitat and environment.

However, low cloud and ongoing rain turned it into a damp squib; it was deemed too dangerous and the six-hour marathon planned for BBC2 was replaced by a back-up programme schedule.

Mr Harron said it would have been a watershed in television history and a landmark show for BBC Scotland. "Technically, it would probably have been the most ambitious programme ever by BBC Scotland," he added.

The logistical and environmental problems of operating in an area so remote were enormous, he said. The BBC, in collaboration with production company Triple Echo, had to comply with a "leave no trace" policy imposed by the RSPB, on whose territory the daunting crags of the Loch A'an basin sits.

The team had to walk some of the kit and personnel in and reassemble complex equipment on the mountainside. Helicopter flights were limited to the bulkiest loads.

When deciding on the location, producers poured over weather history from the past 20 years and found the Cairngorms, on average, to show the lightest rainfall out of the possible sites in Scotland.

"Ironically, this was the safest bet," Mr Harron said. "It was an ambitious project but I certainly don't think it was too ambitious. I don't think it will put us off doing something like this again. Maybe not this year, though. We certainly haven't squandered the family silver on it, even if it was a substantial investment.

"However, my view is that you have to apply the top levels of excellence to a project like this or it is not worth doing at all. We are hugely disappointed but we have to be quite sanguine about it."

Richard Else, executive producer of Triple Echo, said they were very upset. "There were a lot of hard-bitten male climbers in tears today. It would have made a groundbreaking production. Everything worked but in the end the Scottish weather was stronger than all of us and to have attempted any climbing in the Cairngorms over the past two days would have been extremely foolhardy."

Climbers who were due to star in the event included Scotland's leading mountaineer Dave MacLeod, South African climber Ed February and Spain's Araceli Segarra.

The programme would have been broadcast to BBC2 Scotland and shown on the internet in its entirety. Viewers south of the border would have been able to see it through interactive options and part was to be shown on BBC2 for England and Wales.

The ambitious plans came 40 years after the BBC outside broadcast of the climbing of the Old Man of Hoy, a 450ft sea stack, in 1967. The producer, Alan Chivers, said at the time that the whole idea represented a "bigger headache than anything I've done before".