"Prices are now £6 per day (no weekly permit) so I guess I will have to keep going backwards and forward to the car each day to put another ticket on the car! ."

You can get a seven day ticket for the following car parks:
Whitby: West Cliff, Church Street, Marina Back, Abbey Headland, Pavilion Drive and Pavilion Top. They are £6 per day but you don't need to keep buying new tickets.

If guest said "Endeavour" to the tourist office they may have thought he meant Endeavour Warf which has a 24 hour limit rather than Church Street.