"Now this much-loved tree is so wide that the branches are drooping, making it difficult to mow the lawn. We also have to park the car strategically. The time has come for rejuvenation.
"Our pruning of under-branches has allowed the tree to extend upwards and outwards (it is approximately 30ft wide by 20ft high), concentrating the growth towards the branch ends - hence the weight. There are no small branches to prune back to. If we prune the branches back to the trunk, we shall lose the shape we have so carefully encouraged. If we shorten the branches and top the leader by half, will we not be faced with bundles of brittle, unviable twigs or stumps?
"The tree canopy looks full and healthy, but inspection shows a good deal of dead wood inside: twigs that have died back, maybe from lack of light. The tree's habit, in fact, seems to be to form new growth at the branch extremities, self-pruning as it goes.
"Can we rejuvenate and reduce this tree by careful pruning? If so, when and how?"
Mrs Beaufoy spells out in her letter several alternative ways of dealing with her cherry. I think that to barber it all round would be the worst option. Nothing of its graceful habit would be retained, and such treatment will probably encourage bottle-brush growth which will never come to anything worthwhile.
If the tree were mine, and I felt I had to act, I would take a deep breath and take off a couple of the lowest branches entirely. This is drastic, but it would help with the mowing and parking problems and reduce the spread of the tree. This, from what Mrs Beaufoy says, seems to be causing more difficulties than its height.
It seems to me that this is the only way to retain any of the tree's natural growth habit, though Mrs Beaufoy will lose the view of the lower branches that she mentions in her letter.
There is, of course, a risk that the tree, sensing free air and space below, may put out some side branches to fill the gap.
The dead twigs are not unusual in prunus, which as a family are strongly inclined to grow from the tips of the branches. Pruning, though, should be looked on as very much a last resort. Cherries don't respond well to it. If pruning has to be done, it should be carried out in late summer.
The Museum of Garden History is holding an exhibition on the Lost Gardens of Heligan, in Cornwall.
These remarkable gardens were saved by the pop entrepreneur Tim Smit, who started work there in the spring of 1991 and has now restored 57 acres. The garden was originally laid out by the Tremayne family.
Tree ferns are among the rare and beautiful plants that flourish in the mild Cornish climate, and there is also an impressive collection of Himalayan rhododendrons. The old walled kitchen garden has bee boles for skeps built into its walls. All the greenhouses and frames have been restored and now 300 different kinds of fruit and vegetables grow inside the sheltering walls.
The Heligan exhibition opens tomorrow and runs until 29 November. At 7pm on 13 November, Tim Smit will be talking about the restoration of the garden. Admission to the exhibition is free. Tickets for the lecture cost pounds 6. To book, call 0171-401 8864.