I've owned mine since October 1995. The tax rules had just changed on company cars, and my 2.0 GSi Chavalier (J880CYB IIRC) was at the end of it's lease period and coming up to 90K miles. Choice was something 'new' (like a £30K Omega Elite), or something 5 years old (like an LC), or keep the Chavaler on a peppercorn lease.
I should have kept the Chavalier AND bought something 5 years old. I let the Chav go for £1K ('kin idiot). Do I regret not buying the Elite (for £30K), and going for the 5 year old LC instead (for 24K)? Do I need to answer that question? Really? The (now) 18 year old omega would be worth what - probably depend how much fuel was in it! My LC isn't a good example, but it's possibly still worth £10-£15K, although it will never be for sale.
LC's do rust and rot. Rear wheel arches, rear doors, dog-leg door shuts, cills and rear bumper panels are the most prevalent. All these parts are standard carlton so can be replaced/repaired by a good body shop. Don't skip on it though - do it properly. There are mechanical pitfalls too and spare parts can be difficult, but after 18 years of owning one I'm now pretty good at fixining mine.
My Elite is a good car - a good motorway cruiser and the interior is a whole lot quieter and more sophisticated than the LC. But if you want to set your hair on fire every time you drive something, try an LC. Yes it's old, unsophisticated and noisy. But by god it puts a smile on your face on a twisty road.
This car? It'll never sell for £39K. One that's had all the tin-rot cut out and properly replaced might be worth £25K. Perhaps £30K for a pristine example. An average example perhaps £15-£20K. Take off £5K for LHD and another £5K if non standard in any way (wheels, chipped etc)