I would keep on with the Lemsip - not so sure Fisherman's friends do any good.
For razor throat I gargle with lukewarm salty water - not pleasant, but it does give a slight relief.
For those who are coughing at well, try my paternal grandmother's remedy, which was, I believe, her mother's.
Peel and slice a large onion and lay the slices in a basin. Cover with brown sugar. Weigh a suitably sized saucer down on top of this mixture, so pressure is exerted and leave to stand overnight.
In the morning, either before or after breakfast take a teaspoonful of the juice.
Warning: it tastes revolting BUT it works.
My father was of the considered opinion that it works by scaring the cough away, as no-one in their right mind would want to have to take this cough mixture for long. I concur
He also maintained (and he was a doctor) that a cold lasts for two weeks if you take remedies for it, and for a fortnight if you don't.
Colds last winter where bigger and better, so they lasted for three weeks whether you did anything or not. Sounds as if this winter's are the three-week variety.
Hope you all feel better soon.