Them there ducks ask intelligent questions
SC 
They obviously want to know when their pond is going to freeze over.
It may not be a full frost that catches people out from now on, just a very cold night can do some damage to some plants/crops.
You being Luton may not suffer it early but I always keep a weather eye open from the beginning of Sept onwards.
However, last winter it was well into December before we got a frost that caused damage on the allotment. Didn't lose anything though. The garden is quite well sheltered but I didn't get my geraniums or fuchsias in in time last winter, so lost them.
I would just advise you to keep thing sheltered or with suitable cover to easily to hand so you can cover plants you don't want to risk losing.