by business editor Trevor Sturgess

As tension mounts ahead of Saturday's play-off final, Gillingham Football Club’s shirt sponsor is preparing to stump up more cash if the Gills triumph at Wembley.

Just as sponsorship tends to fall when clubs are relegated, it rises when they are promoted.

Kent Reliance Building Society signed a three-year deal worth around £400,000 when the club was in League 1. But that first season, the Gills were relegated to League 2 and the Chatham-based mutual wanted to reduce the amount of money if paid the club.

Kent Reliance argued the club's relegation meant the value of the sponsorship deal should fall. But club chairman Paul Scally was reluctant to concede any significant loss of revenue from the sponsor.

There were lengthy talks between both sides amid speculation that Kent Reliance might pull out if it did not get its way. But eventually, their differences were settled and they signed a revised funding deal for the current season and the next.

At the time, chief executive Mike Lazenby said the society had reaffirmed the contract for the next two years, "and possibly longer".

Mr Lazenby declined to say how much money was involved. But industry sources suggested it was likely to be more than the £55,000 average annual shirt sponsorship for League 2 teams.

Now the Gills are on the brink of bouncing straight back to the higher division, Kent Reliance is facing a higher bill. But Mr Lazenby says he is delighted with the team’s success and will be at Wembley for the final. Last year, the mutual reported record profits and remains the UK's fastest-growing building society.

Mr Lazenby confirmed talks about a new higher sponsorship arrangement would begin before the start of next season if the Gills triumph on Saturday. "It’s part of the deal and I’m happy to pay it," he said.