Mystery is solved - much to my embarrassment! My reason for not believing my car had not got a front camera was because I asked a mechanic at a Seat dealer why I couldn't access road sign recognition on my infotainment screen. He got in the car and also couldn't work it out, until he put his hand behind the mirror hand and announced it had been supplied without a camera. As I was in a hurry I took him at his word and thought no more about it, until I contacted this forum. From the replies I have received I have just had a look and can now see that there is a camera there! I do not know why I never checked before!
I have also read the manual more thoroughly and see that there is an asterisk beside the details of road sign recognition, which indicates that this feature is not available in some countries. Elsewhere on this forum I have discovered that the UK is one of these countries.
Hence my embarrassment. Many thanks for all you replies.