Can anyone offer advice?

The Mepal Molly Men dance twice a year: on Plough Monday in and around the Fenland villages, and at the Whittlesey Straw Bear festival. Someone has informed them that they cannot dance unless they have public liability insurance, thus they sought the advice of the Morris Federation. They now have the cover needed, which doesn't actually come into effect until January 25th, two weeks after Whittlesey! The worst that can happen IMO is someone might get clonked with a broom, so far as I know!

How can the lads get round this stricture (legally) to get round this arguably necessary piece of bumbledom reminiscent of the 1909 recitation voiced by Ashley Hutchings in 'Rattlebone and Ploughjack'?