Just to finish off this topic, I have now fitted the new springs/shocks to the rear of my car.
The springs are rather difficult to remove and similarly, the new springs are very difficult to fit due to the small space between the springs and the body of the shocks.The standard sub £20.00 spring compressors you see on ebay will not do the job as the claws project too much. I tried all manner of attempts, finally giving up and taking them over to my local garage. Guess what, they couldn't do it either. I then tried tool hire shops - they only stocked the wrong ones.
Finished up taking them to a motorcycle repair workshop who did the job in less than half an hour and charged me £26.00. I was so grateful, I actually tipped them a tenner!
The slight difference in spring length has no effect on the ride height.
As a postscript, I was interested to note no discernible difference between the feel of the car with leaking shocks/broken springs and the subsequent drive with those suspension items replaced! Perhaps it's my driving or perhaps the vx is so good, it will still perform to a high standard with defective suspension.
Thanks again for all the messages.
Bob