KYB RX6226 springs fitted in 2011 by previous owner along with a cheap pair of rear shocks. No leaks from shocks, no busted coils. Height from road to arch is 65mm. When rear seats loaded the rear mudflaps scrape the surface over the slightest hump in the road and do the same when cornering left or right. Thinking rubbish shockers

They are standard (NON self levelling) shocks for 3.2 saloon, so they are correct with standard non sl shocks. Failed shocks tend to give a bouncy uncontrolled spring rate. Bouncing the rear of the car by hand should give a push down, release, up down stop action to the rear, and be very hard work to keep the car bouncing by hand. Test in neutral with hand brake off, and chock the font wheels if its in a slope. If it keeps bouncing easily after you let go the shocks are buggered.
Iirc the usual ride height for an elite 3.2 with sl is 675mm. While the shocks do hold the car up, I'd be surprised if the shocks account for 25mm of ride height. So I would also be checking for busted springs. Tbh.