A gradual incline seemed to be the way to do it, so out came the ladder and a length of 4x2 as a check, incase it proved to be too much half way:

In two pushes (me walking up the ladder following) it was at the top and ready to top out onto the roof bars:

Did you spot the critical omisson in the first pic? A little clue:

Yes in my enthusiasm I had forgotten to do this:

Which then resulted in this:

Thankfully no damage done, the 4x2 took most of the energy and snapped in half

Take two...