Heater stopped heating

I just bought a thermostat for a landrover discovery and put it inline in the radiator hose. The part cost $56, I capped the bypass.
It took about an hour and all I needed to remove was the hose.
There is also an inline remote housing available for MG's in the U.K.

Most likely the thermostat has failed and is stuck open. It's a lot of work to change, and it's common on the 2.8L. Here's a pic of my car a few weeks ago when I changed mine (yes, you do have to remove the front of the car - no other way to do it):

http://farm3.static.flickr.com/2456/4026320040_32ef32e2d2_m.jpg

Copy and paste that into the browser. If you're near upstate NY, reply here with contact email address - I can do the job for you.