William Hill, the bookmaker, has issued a thinly veiled threat to move its internet sports betting operation offshore unless the Government changes the tax regime in the next Budget. The company, which yesterday confirmed plans for a GBP 350 million rights issue as part of a GBP 1.2 billion refinancing, said that it was relocating 90 jobs in its sportsbook operation overseas, mainly to Gibraltar — a move widely seen as a warning to Treasury.