I have answered my own question, having changed the rear springs yesterday. It's a pig. Not only did I end up compressing them first but, to avoid overdoing that, I took the 2 bolts out of the bottom links.
It doesn't help having a model with fixed rear seats. God knows why Alfa didn't include folding seats as standard, rather than an option. Apart from the extra versatility drop-down seats would have given the car, my body wasn't designed for squeezing itself into a boot in order to get at awkwardly placed nuts (hidden behind masses of lining, without a cut-out to make access easier).
I like my Alfa but it seems that after they had sorted out style and performance, they gave the job of putting it together to a bunch of people who didn't talk to each other. Every time I work on it, I have to use every tool I possess to undo the myriad of different and inaccessible fastenings, many of which could have been standardised.
But getting back to this thread, I now see where Coxy was coming from!