It depends on which borough you were in. Most Boroughs now have parking control run by private contractors: NOT the Police, the days of a police controlled warden giving you a few minutes grace are now long gone- you were very lucky they didn't clamp or just lift the car the second the time ran out- that's what happens in some boroughs; I work in Waltham Forest and it happens all the time outside my office window!!!
It may be different in Darlington where presumeably the Police are still involved in parking, but in London these companies will pursue you with religeous fervour. They have photos- this is what they use for evidence, plus no doubt they'll drag up some CCTV evidence as well-I would suggest you just pay the fine. You can fight it, it'll cost you time and stress, and in the end they'll still very likely win.
Another thing to watch out for now, particularly in Barking and also Newham, is that they no longer even need a warden on the ground- the tickets are now issued using purely CCTV evidence. Pull over onto a yellow line, and the photos and fine notification appear through the post a week later- don't ask me how I know!!