Thanks chaps - sod's law, I've fitted it over the seat catch, mainly because the catch is already shaped to fit the curve of the bodywork, whereas the rack is flat. As expected, the seat doesn't latch down, but then again it never did unless I fiddled around with it.
Lambretta LI125 Series 2, Lambretta LI150 Series 3, Lambretta J100 Cento, LML Star 150 2T
And if the back of the seat gets raised enough so that the seat can rock from side to side whilst your butt is on it - the hinge at front of seat will crack.
That's an interesting point. At the moment, the seat catch is in the same position it was before (sitting directly on the frame), so I maybe it's better that way?
Lambretta LI125 Series 2, Lambretta LI150 Series 3, Lambretta J100 Cento, LML Star 150 2T