stairs lighting switches

[Taylortwocities]

The 2 nearest are the lounge and the upstairs light, how do I know which is the previous light?

If your house is wired with two lighting circuits (usually upstairs and downstairs) then USUALLY all of the downstairs lights will be on the same circuit. So USUALLY the upstairs light will not be on the same circuit as your problem one.
Electricians USUALLY will use the shortest or easiest cable route from point A to point B so the lounge light would be a decent guess.
There are better, more certain ways of determining this than guesswork, but you would need time, competence and the right test gear……

 

[Damien91]

The lights are all on one circuit so both are still an option unfortunately, I'd ask what methods can be used to determine which is correct but I'd likely just get shouted at.

 

[ban-all-sheds]

There are better, more certain ways of determining this than guesswork, but you would need time, competence and the right test gear……

Those are the only ways it should be done.

"By guesswork" is a stupid thing to do, and anybody who advises it or assists it is being highly irresponsible.

Nothing bad is going to happen to the OP if he has to live with the current situation until he has acquired the necessary competence. The same cannot be said if he goes fiddling with things he does not understand.