sorry clear I missed that bit about the caretaker, I would make allowances for him getting tied up happened to us in an customs and excise building, the caretaker is usually the goffer and everyone wants him so he could be popping back and forward
I recon 2 hours inside - 2 hours outside 1 hour excess
total 5 hours based on £30 hour £150, remember you might need to get cars moved etc
is this close to what you where thinking
jinky