Buying 2nd hand Defender 110. What to look for

This is my story. I'm living in Limerick, Ireland. Need to buy the best 4x4 ever made. Hence decision to chose Defender 110.
My work has now extended into Site suitability testing. This means I will be driving into fields in all kinds of terrain in all kinds of weather. I will be pulling a trailer with water tank.
I'm looking at 2nd hand Defenders on ebay and at some of the vehicles on sale here.
The big question is 'What should I be looking out for to ensure vehicle isn't a complete wreck?'
Obviously this list could be endless so I'm only looking for hints as to the big things to look for.
I am not mechanically minded.
Hope some of you guys (girls) can offer advice.

its like everything all comes down to budget,petrol/diesel,td5,200/300 tdi answer theese simple questions and you will get more specific answers

Apart from the basics eg engine, gearbox etc all working properly the biggest thing is rust. Check the chassis over thoroughly and pay particular attention to the rear crossmember, outriggers and the areas around the suspension mountings. Then have a good look at the bulkhead esp. the top corners under the windscreen and the footwells. Give it a good test drive looking out for dodgy handling esp. under braking, and any untoward clunking or knocking from the drivetrain. Best policy if you haven't owned a Land Rover before is to take someone with you that knows them.

Thanks guys.
Looking for Landrover defender TD1 200. Budget between £5,000 and £7,000.
I have learned a great deal trawling this forum. Love the old Landrover but would not have the time to keep one maintained.
Landrover and parts are way more expensive in Ireland. Many, if not all, enthusiasts go to UK to buy. It's not practical to fly someone with me to look at a vehicle and then not but it. I am more likely to risk buying something after going thought check list of critical items.
I may be wrong, but I feel unlike buying a regular car, a Landy is less likely to be completely clapped out.