How would you deal with this issue?

Susi, If there are no visitors (or MAs of a nervous disposition) in earshot I probably will .................. mind you its cruel to get into a battle of wits if your adversary is poorly armed

Just ask them what their problem is.  Or be a little less subtle and go with the "Do you realise that everyone thinks you're a massive wanker?" approach.

I think that would go over their head (pun intended)

People dont do things against you they do it for themselves and this person is probably unconscioulsy unaware of their behaviour and how it is affecting others. You don't know what you don't know. By talking to this person about how you are percieving their behaviour you may just help them, also perhaps look at why this persons behaviour is triggering you to feel this way? Is it something you need to deal with and change? It's very easy for us just to look at the other person and rarely do we look at ourselves. If someone is affecting me I will always look at why? what is it that they are triggering in me? and then deal wth myself. Dealing with me first allows me to have a non emotional view of the person next time I meet them and invariably their behaviour has no effect on me. People are not their behvaiours and if you can help the person see their behaviour may be percieved as negative bysome you will be doing them a great favour. By looking at yourself and the other person taking this viewpoint its a win win situation. Non of us are perfect and can always do with a little reflection.

Have a gorgeus day x

Debbie, thanks for the well considered reply. I think you are right in that they are not deliberately trying to wind me up. I'll probably just have a quiet and brief word if it happens again, but I don't feel inclined to have a deeper discussion.