In my role as Tree Officer in the Planning Department of Warwick District Council I occasionally get the opportunity to review urgent requests from tree contractors to fell a protected tree that has become, in their opinion, a bit of a risk, i.e. a 5DN.
If the tree is the subject of a TPO then to satisfy the requirements for a 5DN under Regulation 14 of The Town and Country Planning (Tree Preservation) (England) Regulations 2012 the tree must either be dead or it must present an immediate risk of serious harm, and the only works that can be undertaken are “works urgently necessary to remove an immediate risk of serious harm, as soon as practicable after the works become necessary”.
If the 5DN is accepted, and having abated the immediate threat, a routine application for consent to carry out works would then be required and it would be processed in the normal way.
The fun starts if the 5DN is not accepted and all sorts of hoops must be leapt through, but that’s another story.