It’s £16.50. Get a grip.
When you consider that the US has a similar setup and only charges $5 for 3 years, welcome to ripoff Britain.
One question that doesn't seem to have answer as well, if you register your drone, and fail to renew it a year later what happens then, do they come knocking on your door? Do you get bailiffs demanding payment or will you get the Police knocking on the door ready to drag your criminal a$$ to prison for non payment of the drone license.