Hi Antha. Sorry to say this is a frequent occurence with Pansies . best remove any affected leaves. I think the damp autumn made it worse this year.
Don't plant Pansies in the same place next year . I think it may carry over in the soil.

I have had it badly on my violas this year, but not on my universal pansies! spraying seems to help my violas.

Its called 'Black Spot' not surprisingly lol
Yes cut back affected leaves and spray (just one from local garden centre for the above disease) as well its best to have 'belts and braces'
Violas and pansies all get it but can come through it if action is taken.
Good luck:)