When is self-help available?
Macnab v Richardson
 EWCA Civ 1631
The slightest encroachment on another’s land is a trespass (Ellis v Loftus Iron Company (1874) LR 10 CP 10, at page 12 per Lord Coleridge CJ). However, that does not mean that the court will automatically grant an injunction. Nor does it mean that the owner of the land on which the trespass has taken place has an absolute right to use self-help to end the trespass. The principles of self-help are set out in the case Burton v Winters  1 WLR 1077 in which the following passages appear:
“Self redress is a summary remedy, which is justified only in clear and simple cases, or in an emergency...In this case there was a minor encroachment by the mesh of a fence (but not the fence posts), which constituted a technical trespass. However, applying the principle in Burton v Winters the Richardson's were wrong to move the McNabs fence whilst they are away.
Ever since the assize of nuisance became available, the courts have confined the remedy by way of self redress to simple cases such as an overhanging branch, or an encroaching root, which would not justify the expense of legal proceedings, and urgent cases which require an immediate remedy. Thus, it was Bracton’s view that where there is resort to self-redress, the remedy should be taken without delay."