Chair on a £100 budget?

[willhub]

Looking for something around 100, I don't spend hours on end at the desk, but I want a chair that is comfortable should I spend a few hours at the desk. It doesn't have to look cool and sporty like a chair out of a Ferrari but I definitely want to find the best bang for buck. Needs to support my back properly also.

Thanks
Will.

 

[willhub]

5ft 10, weigh about 13.5st unfortunately.