Are quinces grafted? What do with my 'dead' quince tree?

Marguerite, Thanks for the advice. I'm pretty sure from what you say that all the growth above the graft is dead as there's been so sign of any buds since the spring. We've had quite a few grafted trees die on us, but usually apricots and peaches, but there is usually growth from the roots from the rootstock. I suspect we will just need to buy a new quince tree and treat it more carefully, though I could try grafting something on to my seedling quinces I guess.
Why is it that the things we like most won't grow in the type of soil or climate we have? In the UK I spent all my time trying to grow melons which wouldn't ever ripen, and now we are in France and melons grow well, I am fed up I can no longer grow raspberries and loganberries successfully!!

That's life, Bertie, I'm afraid - you pay your money and you make your choice and you can't have everything;-)

You are right, Marguerite. But I think all gardeners struggle to achieve the (virtually) impossible. I envy you your tropical garden, but we do succeed with edible passion fruit here (under cover). I've once fruited guavas, not that they tasted that good ripening in cold conditions. Paw Paws always die during the winter. My Feijoa hasn't set fruit despite lots of flowers, neither has my pomegranate. But one day I will get one fruit and think it was all worth it!
Anyway, I must get back to planting leeks. They grow well here at least like most other essential vegetables, though I'd guess you'd struggle with them in the tropics!