Interesting bad soil problem...

Houston, we have a problem.

I've been a little concerned about the soil in my front garden, so tried a little experiment. I had a few spare tomato seedlings, so after leaving them outside for a week or so to acclimatise them to the cold, I planted them into the soil directly, with plenty of water etc. Within two days there was a real transformation - the leaves became very bleached and almost cigarette-paper thin, and silvery on the undersides. 

Any thoughts on what is going on? This area of the garden is usually rather wet, and I think we're seeing the effect of acid soil. The undersoil is very compact, but usually waterlogged, and couch grass is a big feature. I'm planning to put down a load of lime, but would appreciate any advice!