Ok so I checked the solenoid, bridged the contacts and got the same very slow turn over. I have tried retarding the timing by turning the dizzy and it seemed to make no difference. I am going to remove the positive cable that runs from the solenoid around the back of the engine to the starter and check it for damage. If that doesn't yield any results I may have to bite the bullet and pay someone to fix it. Bugger

It'd still be worth connecting the battery negative to the chassis and the positive to the starter motor with some jump leads to eliminate the high current wiring as a source of the fault.

In your original post, you've replaced the battery! Was there a reason for replacing the battery?

Do you still have the old battery? If you do! I would refit it.

Timing!! The engine timing being out, wont flatten the battery. If anything, it will take ages for the vehicle to start (or it wont start) and it will run like a bag of nails.

You can buy a timing gun from any good motorfactors or machinemart (£20-£30) they'll be instructions in the box

My gut feeling is: faulty battery OR a bad earth.