Thank you Malc it's a ls430 2001 REG MT51 GWW Feel free to check out the Mot history if you would like to see the exctent of it all.
Yes of course I purchased the car for 2600 pounds with 11300 miles on the clock, A real deal I thought as it came with almost full service history and I had a good going over the car with no visible rust in sight other than a few stone chips being my dream car I had to jump at the opportunity. I've since spent quite abit on the car getting a brand new radiator fitted. New calipers, discs and pads up front and same at the rear, a gearbox flush and fluid change. Flash forward to today when I got the news the rear Subframe was "F*cked" I went down and took a look at it and it's a sorry sight it seems that the car is rusting from the inside out above the subframe. I'm still not sure where to go from here I thought about selling the car for spares and repairs but It just doesn't seem right.
Josh