Zooming in makes the image too blurry, but are you able to discern the number plates on the original photo? Not specifically the numbers/letters but the format, in the hope that it might help with the country at least, though they may have driven to the continent in that Zephyr. 
I think this building is in Europe somewhere rather than Great Britain. The windows behind the arches in the ground floor are interesting, but it’s hard to determine “depth of field” so I can’t work out how far behind the stone arches they are. Not that it helps with location.
Are there any other photos in the collection which include the same car/s or the unknown woman?
Thanks Ruskie, it is very difficult to make out the number plate on the original too. It is possibly 3 figures (numbers or letters - to hard to say) a gap, and then 2 figures.
The windows on the ground floor do seem to be quite deeply recessed. I think there are flower boxes in front of each window near the citroen.
No other photos of the same building or car. So many photos have been in a shoe box for a very long time, and are quite mixed up, hard to put in any kind of order - I'm trying to sort them out and put them in albums. Very time consuming, but enjoyable too.
Your grandparents must have been quite wealthy to take that trip in the 1950s/60s. It wouldn’t have been the norm.
Ha! I wish. No they weren't particularly well off. My grandfather (in Australia) worked for a Swiss wool company. I think this trip was part work related. They certainly did spend time in Basel, but also toured around the UK and definitely France, Luxembourg, Liechtenstein, Germany. Maybe some other places too. The photos of Switzerland are generally all together in a separate group, though as I mentioned the shoe box of photos has been mixed up a bit over the years.
