Originally Posted by luckylady:
“If the show is to be 16 weeks long this year it would have to either start on 5th September (to have the final the weekend before Xmas as usual) or on 12th Sept (which would have the final being on Boxing Night!)”
If there is 16 couples, it only needs to be 14 weeks long because 3 leave in the last week (the final)

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It probably is 18/19th September when it actually starts, with the weekend before being when they've usually shown the preview show.