daltontrees

That's not hawthorn. Rowan or whitebeam maybe

almost certainly silver birch Betula pendula.

Not good pics. Could be Stereum hirsutum.

They're a mystery. Their main susceptibility is honey fungus. Heterobasidion and Phaeolus have been reported in the USA. I have never seen any other fungal association except very slow degradation of long-exposed wood.

I may be wrong but as far as I know there can't be any liabiity in nuisance or negligence for heave on a neighbour's property. I mean, in theory there could conceptually be liability in very particular circumstances, but I have never heard of it or seen it mentioned as an insurable risk.

Maybe the 3rd one but it's not possible to say for sure. Apple is pretty nondescript still it starts to develop some bark shedding and cracking. Give it a sniff, apple wood is quite distinctive.

Mixture of cherry and plum.

Too late to do anything except cut any ragged end cleanly.

I don't doubt the mapping. But there is a world of difference between the subsidence/heave loadbearing characteristics of firm (overconsolidated) shrinkable clays and clay soils including tills. Tills in particular usually have a silty or sandy component that substantially reduces the shrinkability. They are alos rarely overconsolidated. It is exceedingly rare for them to be so pure of clay and so consolidated that they present anything other than a small one-off risk of settlement. Local knowledge may give the location of any such areas.

There are no shrinkable clays recorded in and around Yarm by the British Geological Survey. East of the A19 there might be.

My first question is where is this? Is it in an area known for shrinkable clays. If it's not then you are not looking at tree related subsidence or heave. I'd get that Leylandii away on point of principle, horrible and ill-concieved and only going to cause some kind of problem eventually. It's obviously there for privacy, but I'd bolt some posts to the wall and put a trellis up above wall height and get some light climbers in, like clematis, jasmine maybe honeysuckle.

It is always useful to appreciate that the 12x RPA is not based on any science, it is a figure plucked out of a lucky bag. The rest of the english-speaking world deviates from it systematically based on species, age, condition, tolerance to disturbance and so on but the UK treats it like it is evidence-based. The other ever-refreshing perspective is that BS5837 is not the law, and says itself that deviations from its defaults can and should be justified. Most conifers in my experience haven't read the Standard and don't do 12x. The bigger they get the more overkill the 12x becomes. An additional perspective is that if your neighbour's tree is preventing you using your land, that is a common law 'nuisance'. You are under no obligation to protect the neighbour's encroaching tree roots. And finally the planning system is not there to protect private property, it is there either to ensure developments have adequate amenity or that publicly visible important amenity trees are kept in the public interest. The planner's shouldn't be arbitrarily protecting the tree without overriding public interest.

Tha's horrendous!

Doesn't look fungal at all. There's been a long bark split, or more likely an abrasion or tear, exposing a strip of wood that has some very superficial decay or oxidisation. It's occluding. The roughening of bark may be caused by the insect associated with beech bark diease but if the fungal element isn't present then it's not BBD. Looks like pretty meagre growing condtions. Is that s a brick wall immediately behind? Could do wit seeing overall crown conditions to know if this bark condition is the cause of or symptom of decline.

Am i reading this right? I don't see the neighbour saying that you would be resonsible for heave. Indeed, you wouldn't be in any circumstances. According to the borehole analysis, it might turn out to have been a bad idea to insist on removal of the tree, since the heave potential is significant. A dead tree draws no water and cannot cause further subsidence. I can't see why removal of a stump would be necessary.