Thanks for posting these photos. Our R4 comes from Slovenia and was built in 1990 and imported to the UK in 1993. It is the light metallic blue colour like in the fifth photo from the top. It has a 'hard' headrest with the hole in the centre which I've only seen on Slovenian R4s. We've only got one headrest though, so are looking for another one!
Malcolm, good idea about ordering by year (oldest first); not sure my navigation is up to being near the front!