I had the same with my VW earlier this year. The issue might not lie with the cable, but instead with the handbrake mechanism by the rear calliper that provides tension to the cable. Corrosion usually prevents it from returning back to its proper position, resulting in the slack cable.
Cheers, I hadn't thought of that, and it seems likely that's the problem. Either that or it's snapped further down the line. If I can get access to the back of the caliper with the car where it is I might try a careful squirt of penetrating oil and see if it frees it up for a bit.
I had the same with my VW earlier this year. The issue might not lie with the cable, but instead with the handbrake mechanism by the rear calliper that provides tension to the cable. Corrosion usually prevents it from returning back to its proper position, resulting in the slack cable.
https://www.youtube.com/watch?v=JnGfPQKLR7I
Could also be an issue with the calliper itself.