Truro cathedral - the big lunch

Went with family to the 'big lunch' which was supposed to be outside Truro Cathedral in the gardens, but due to rain was hosted inside. Never before have I seen a bouncy castle inside a church let alone a cathedral and also pimms served - what's that all about ?
We set out our picnic blankets, (as you can see at the front of the photo), popped open the prosecco, dished out the egg and cress sandwiches and joined in the fun - it was surreal but great.
Don't know why all cathedrals don't contemplate it ( may suggest it to Southwell)