Hello Teacup,
A 'Grockle' is a holiday-maker. The term originated, I think, in the West Country (Somerset, Devon, Cornwall), and is generally meant derogatorily (and having spent many years in the hotel and catering industry, I know why
).
There's a disconcertingly growing number of holiday-makers in this area (the Bournemouth-Poole-Christchurch conurbation) who instead of booking into a local hotel for a fortnight or so are now buying up seafront or near-seafront property to spend a few weeks a year in. In many cases these properties are left empty most of the time. Some places (very modern and totally lacking in character) overlooking Poole Harbour are fetching literally millions of pounds.
Alex