In Midland Bank v Bardgrove Property Services and others (37 Estates Gazette 126, 19 September 1992), the defendants were a property development company, a building contractor and engineering firms involved in developing a site in north London.
The site adjoined land owned by Midland Bank. In 1985, it was excavated, exposing a vertical earth face at the boundary, and temporary shoring was erected by the contractors. Some subsidence occurred on the plaintiff's land, including damage to a roadway, but this was repaired and no further damage took place.
In the same year, the contractors erected a permanent retaining wall at the boundary edge, but it was accepted for the purposes of the legal action that this was inadequate. Expert opinion indicated that there was a probability of rotational collapse occurring at some time between 10 and 20 years into the future. No further movement occurred for two years, and the Bank then decided to take steps to prevent this collapse occurring, and carried out stabilising action on its own land - at a cost of £230,000.
At common law, owners and occupiers of land have a natural right to support of their land, and interference with this right - by, say, excavation works - gives the right to legal action, a form of private nuisance. The Bank sued the defendants for the recovery of its costs, and the central question of principle was whether actual physical damage was a necessary ingredient of the action for interference with support.
It was accepted that the early temporary subsidence was not relevant to the main case. Not unnaturally, the Bank argued that it would be unfair if it was penalised for acting prudently. Presumably, its expensive works would prevent any subsidence occurring in the future, and if legal action depended on damage it would never receive compensation.
The Court of Appeal undertook an extensive review of previous authorities, examining in particular cases concerning mining subsidence from the last century. Eventually, it decided that damage was a necessary element of the action, and since no damage had occurred in this case the Bank's action failed.
According to Sir Christopher Slade, "the owner of land may excavate and remove that land so long as he does so in a manner which does not interfere with the adjacent owner's right to enjoy his land in its natural and undamaged state; the adjacent owner's cause of action does not arise unless and until damage actually results from the excavation."
The courts' reluctance to handle anticipatory cases of this kind is partly explained by the difficulties of assessing evidence based on future risk and possibility. Midland Bank's position was certainly not helped by its apparent failure to give the defendants an opportunity to carry out or contribute towards the improved remedial works themselves. Whether they would have agreed to the extra costs involved is another matter.
The Court of Appeal, though, did offer one potential legal life-line to landowners faced with a similar position.
The courts have traditionally been prepared to offer one legal remedy before damage actually occurs, namely the so-called "quia timet" injunction - a court order to prevent a nuisance or similar tort occurring. According to general principles, these are granted only rarely and in cases where the likely damage is both "substantial" and "imminent". A homeowner, for example, could seek such an injunction against his neighbour whose dead tree was about to fall down on his house and need not wait for the accident to occur.
A probability of subsidence occurring 10-20 years into the future certainly cannot be described as "imminent", but Sir Christopher Slade hinted strongly that the courts would treat such an application sympathetically. "It should not be assumed," he held, "that the state of our laws was such as to leave the bank in the summer of 1987 with no options except that of either waiting for the anticipated further damage to occur in 10 to 20 years time or doing the remedial work themselves without hope of obtaining recompense."
In the meantime, and until the courts develop firmer principles on the issue, the common law message must at the very least be: do not carry out expensive preventive works without warning if you want to recover the costs of doing so from someone else.