when i have picked the last of my runner beans, is it a case of cutting down the plants and starting again or will they grow again?
Cut them down - leave the roots to decompose in the soil as they will have grown nodules on them that are full of nitrogen, so they will fertilise the soil.
Afraid we have to start again next spring with new runner bean seeds - but if you're a bean fan you could sow some Broad beans - Aquadulce Claudia - in October or early November - they'll grow into stocky little plants through the winter, and when the milder weather comes they'll race away so that you get an early crop by the end of May if next spring is better than last
Many years ago 3 or 4 of my runner bean roots, left in the soil over Winter, sprouted and grew again in the Spring. They are perennial in their native habitat, but it takes a special set of circumstances for them to survive in the UK. I think it must have been a mild, dry Winter that year. It might be possible to lift and store them like dahlias but I doubt the effort would be worth it considering how quickly they grow from seed.