A lot of coal subsidy is paid by EU to compensate for communities destroyed by phasing out coal and it is no longer economic to mine
EU money has certainly gone into ex-mining areas in the past, but coal does not receive a direct subsidy as such in the UK. Most of the coal used in the UK coal fired stations comes from outside of the EU, Columbia, USA, and Russia. If coal fired stations were being used as they were intended, i.e. as base load generation, they would still be the cheapest form of electricity generation at current commercial coal prices.
The reason coal fired generators are being overpaid, you can call it a subsidy if you like, is because they are bidding for lucrative winter back-up capacity contracts, the next of which in this February for 2022. The one nearest me missed out on 2020/21 auctions, but is bidding again for 2022. If they fail to secure a contract, I would think it would be closed by 2020 - they have a derogation on emissions until then, and to operate beyond this date they will have to spend money on new plant, or reduce output. They all have to close by 2025, regardless.
These coal power plants are now operating in a manner they were never designed to, i.e. providing short term capacity at peak times. I don't have to check gridwatch to confirm this, I can see and hear it from my kitchen window... at this time of year, they ramp up from low fire at tea time, and the air breakers disconnect from the national grid in the very early hours. I've lived here for 18 years, and it was not that long ago that this 2GW station basically ran flat out, 24/7 for 50 weeks of the year.
This new routine is destroying the boilers, I know people who work on the outages there... they are spending as little as possible and running the plant into the ground. I'm afraid coal fired generation is on it's last legs in the UK.