It is very rare on a water like Tenterden that you can't get a few fish, even on a hard day.
Winter tactics can be a little different from spring or summer, but you can catch if you use the right pattern and mast important - fish it at the right depth.
One of the very best imitative battern to use in winter is the bloodworm, especially a gold head bloodworm which will fish deep.
Find some deep water and stand if you can with the breeze coming over your left shoulder if you are right handed. It often pays here to use a strike indicator on the leader. (listen to the howls of derision from the purists)
Adjust the strike indicator until you find the correst taking depth. Cast out with a floating line and allow the breeze to drift the line sideways. Only retrieve sufficiently to keep in touch. When the line is at an angle of 45 degree, start a VERY slow retrieve.
Learn the "figure of eight and drop" retrieve by the way.
Another way is to use a slow sinking line with a fly such as a Viva or Orange Blob.
(more howls from the purists)
Count down each cast until you get a fish and then remember how long the cast was counted down. You should get several fish this way. The best retrieve for these flies is the hand over hand or roly poly retrieve. (more howls)
If it is allowed, the booby fished deep is one of the deadliest cold water tactics of the lot. Use a very fast sinking line. A Di 7 or Deep Rio 7 is ideal. Unfortunately these lines are not easy to cast. Wear a wide brimmed floppy hat and specs when casting these lines. Forget baseball caps for goodness sake.
Tie a short leader to the end of your line, say about 18 inches long and tie the booby to the end. Cast out over deep water and allow the line to sink right to the bottom. The booby will pop up of course.
Trout often take the static booby and swallow the fly. Try twitching the booby back and feel the line for takes. Often the takes are very delicate. You can also try another pattern fished this way called a rasputin. It's just as deadly and might overcome the "No Booby" rules.