The paso dobles have been practised, the crooning rehearsed and the fake tans topped up. Tonight marks the return of the great Saturday night entertainment battle between BBC One and ITV.

As Strictly Come Dancing returns to our screens for a sixth series and the nights begin to draw in, broadcasters are vying for their share of those stay-at-home families whose Saturday evening spending has been cut by the credit crunch.

At the heart of the contest will be the familiar mainstays of the two talent shows. First, at 6.30pm, will be the BBC’s ballroom-dancing season debut, followed at 7.30pm by The X Factor on ITV, which already draws more than nine million viewers for each show.

Owing to the huge crossover in audiences between the two, the broadcasters are loath to go head to head in a competition that Strictly Come Dancing usually wins. Much will depend on the success of Merlin, the BBC’s big-budget series that begins a week today.

BBC executives hope that the 13-part drama, a retelling of the Camelot legend that imagines the teenage interaction of Merlin and Arthur, will outperform Robin Hood, which last year failed to match the performance of Doctor Who in the same slot.

Elaine Bedell, the BBC’s controller of entertainment commissioning, said: “There’s no question that there seems to be a rejuvenation in communal viewing. Both with us and ITV, people are sitting down together on Saturday nights desperate to watch the shows, because however many catch-up services there are, they know people will be talking about it the next day, and they want to be part of that.

“There’s no question that people are tightening their belts. If we can provide a bit of extremely enjoyable escapism on Saturday nights then I hope that gives the viewers something to enjoy. I know that there are loads of families that want to watch both Strictly and X Factor. It’s a shame when they go head-to-head, but it’s inevitable sometimes. We don’t want too many arguments in households.”

Tonight’s first instalment of Strictly Come Dancing will introduce the 16 couples taking part, including Heather Small of M People, Rachel Stevens of S Club 7, Phil Daniels and John Sergeant. The show attracted more than 12 million viewers in last season’s live final.

Those switching to ITV afterwards will see Simon Cowell and his fellow judges travel to Cardiff to pick the best of the Welsh talent on offer for The X Factor’s boot-camp period. Last week’s edition attracted 9.02 million viewers.

Next Saturday Merlin will be broadcast at 7.30pm, in a direct challenge to The X Factor and the slot in which Robin Hood was heavily criticised. The new drama has high production values and a cast that includes Richard Wilson and John Hurt. Its one failing may be its fear factor: children at a preview screening on Thursday night could be heard telling their parents that they found it too scary.

Anna Home, the chief executive of the Children’s Film and Television Foundation and a former BBC head of programmes, said: “To a large extent these things go in cycles, but there is a feeling around the broadcasters that in this age of multichannel television, there needs to be a repository for programmes that the whole family can watch, and that is Saturday night.”

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