What's the probability? My Gite advert on 4OD

I have recently taken out an advert on Holiday Lettings.co.uk for our farmhouse rental near Josselin, and much to my surprise today I saw a banner advert for our Gite!

I was viewing the Channel 4 TV 'catchup' service 4OD, to try to watch an episode of Time Team that my father recommended to me as they were digging in York, which is where I went to University (an awful long time ago).

And there, in the banner advert at the top of the 4OD website was an advert for Holiday Lettings, with links to two of their Brittany properties, including on the right, my own holiday Gite.

I was at first incredibly surprised at the probability of being served an advert for holiday lettings, and then for there to be two featured properties that included my own. After a while I figured that it was probably the cleverness of Google Advertising that had worked out that I have sometimes searched on Google for Brittany holiday Gite's, and that this was thus a good advert to serve to me. However having refreshed the 4OD page several times since I've been shown adverts for Aviva Insurance, Audible spoken word books, Thomson Holidays and now Marc Jacobs fragrances, so I am not convinced it was clever Google after all.

Here's my full browser window, showing the advert in context:

Well let's hope the bookings come rolling in !