I too am in the UK with an N54 forum and couple of years back had the same thing with such unwanted ads ... it seems GOOGLE, as Nick enquires, is the biggest offender==anything for money then!!
I contacted the N54 admin folk and Nick kindly responded with simple help ..... suggested I paid for LEVEL O upgrade which got such ads removed, we were so impressed I later moved up to LEVEL 1 and OFF CAME THE LOT on the day they said it would and in English terms the cost wasn't that much either ++ you get better forum functional availability thrown in.
I use a MAC computer and will tell you that I certainly didn't see some of the complaint stuff but some of my members made me very aware they were like you are now.
I'm not that computer literate as they are simply inanimate objects with an on/off switch but since the upgrade, which will be renewed, has been in use the full 'search' facility is most useful.
Go with Nicks advice..
Scoring disabled. You must be logged in to score posts.