Paint went hazy

[ging84]

I tried to do a diy repair on a scuffed door, i used the same process i did on a repair earlier in the year which gave me a really good finish. This was to do several coats of paint, rubbed down with dry P800 20-30 minutes after painting between coats. The final coat was not rubbed down at all, left for 20 minutes and then given 2 coats of lacquer leaving 20 minutes between coats with no rubbing down. This gave me a really good finish last time, but this time completely hazy.
The 2 main difference are that it was a bit colder this time, and i got the paint off the shelf from halfords.

What do you think went wrong? and what should i do to sort it out?