symphonyangel,
I beg to differ. The 21 m visitors are not ones to the theme park, but ones to the resort as a whole, and include both leisure and business tourism. Blackpool is the UK's largest conference and exhibition centre, not hard to see how they could attract so many people. The illuminations attracts millions, pleasure beach around 7 million - BLK is a much bigger resort than most people think.
This is BLK's unique selling point, and the reason it can co exist quite happily with LPL and MAN, and not have a real impact on operations there, as someone above pointed out, take the Ryanair services as a perfect example.