How long do classified ad pics take to update?

[Zippee]

I had my ad submitted about half 1 (http://www.pistonheads.co.uk/sales/3313807.htm) and realised I'd uploaded some thumbnail pics by mistake so edited with the correct pics shortly after. However, the live ad shows the old fuzzy pics but when I go to edit the new updated ones are indeed there.
I'm assuming it's just me being impatient but how long should it take for the new ones to go through?

[MattDell]

Should take a few hours (not sure the exact interval, to be honest, but no more than 12 hours). Our pages are cached to ease load on the servers, so that's why it doesn't update immediately.

[Zippee]

Thought it may be something like that - thanks for letting me know