Right, so I've now measured the ride height. ( I ended up using an old metal tape measure cut off at 180mm to measure the front subframe height, very easy to get an accurate measurement ). The front measured about 5mm high but I didn't have two humans available to sit in it so I'd guess its about right when correctly loaded. The back however is running 15mm below spec ( again without anyone sitting in the car! ) The springs and dampers are original standard fit, rear suspension bushes are all newish. Correct size wheels and tyres inflated to spec. Low mileage car but the springs and shocks are now 25 years old (fronts were replaced a few years ago). I would therefore say they are the most likely candidates for the ride height discrepancy. Is there anything else I should check / consider?.