Thanks JandS, the ads shown are Google Ads so will be different each time , it's probably picked up that you have visited the Post Office website at some point....it's clever like that.
I can't seem to replicate the issue you are getting, what phone are you using?
I have edited the code so the ad drops down as I could originally see the issue you were experiencing, it could be a cached page potentially; when you are faced with the homepage if you press refresh in your browser does this rectify the issue?
Thanks.