Three years ago my much-loved laburnum tree was cut back so ruthlessly by a so-called "expert" that he killed it and I had to have it felled. Since then it has sprouted dozens of vigorous, 6' - 8' tall shoots from the base of the stump. Will any of these develop into a tree, and what can I do to help them?
Sure! Just cut all but one leader shoot, and care for that one. Keep all others cut. This article will help you to care for it:
https://www.gardeningknowhow.com/ornamental/trees/goldenchain/growing-goldenchain-trees.htm
That's great news and really helpful. Thank you very much.