A Tree Preservation Order, universally shortened to TPO, is an order made by a local planning authority to protect a specific tree, group of trees or woodland. It is the single most important thing to establish before any tree work in South London, because the consequences of getting it wrong are criminal rather than civil.
What it actually prohibits
Government guidance is specific. A TPO prohibits the cutting down, topping, lopping, uprooting, wilful damage and wilful destruction of protected trees without the written consent of the local planning authority. The Secretary of State also takes the view that cutting roots requires consent.
That list is broader than most people assume. Lopping a few branches back is prohibited, not just felling. So is damaging roots, which is how a great many TPO breaches happen: a driveway, an extension foundation or a trench for drainage severs the root plate and the tree dies eighteen months later.
Trees of any size or species can be protected. There is no minimum size below which a TPO stops applying.
The penalties
Section 210 of the Town and Country Planning Act 1990 sets out two tiers.
For the serious offences, cutting down, uprooting or wilfully destroying a protected tree, or damaging it in a way likely to destroy it, conviction in the magistrates' court brings a fine not exceeding the statutory maximum, or twice the value of the tree, whichever is greater. On conviction on indictment in the Crown Court the fine is unlimited.
For lesser contraventions the penalty is a fine up to level 4 on the standard scale.
The Act also directs the court to have particular regard to any financial benefit that has accrued or is likely to accrue as a result of the offence. That matters, because the usual motive for illegally felling a mature tree is a development that becomes more valuable without it. Fines in reported cases have run well into five figures.
How to check before you do anything
Ring the tree officer at the relevant borough council. In this part of London that will be Southwark, Lambeth, Lewisham, Wandsworth, Bromley, Croydon, Greenwich, Merton or Sutton, depending on the address.
Most boroughs publish a searchable map of TPOs, and the tree officer will confirm both whether a TPO applies and whether the property sits in a conservation area, which brings its own separate rules.
Do this yourself rather than relying on the tree surgeon. A reputable one will check anyway and will refuse the job without confirmation, but the legal responsibility sits with the tree owner.
Why this matters more in South London than most places
The area has an unusual concentration of protected trees. Dulwich, Blackheath, Greenwich, Wimbledon and Crystal Palace all have extensive conservation areas and large mature street and garden trees, many of them individually protected.
There is a second, local complication. Much of South London sits on London Clay, which shrinks and swells with moisture. Mature trees draw water from that clay, and their removal can cause heave just as their presence can contribute to subsidence. Insurers sometimes want a tree removed; the council may refuse consent. That conflict is common enough here that councils have a settled process for it, and it needs an arboricultural report rather than a chainsaw.
The exemptions
Dead trees are exempt from the consent requirement, but you must give the authority five working days' written notice before the work.
Work is also exempt where a tree presents an immediate risk of serious harm and the work is urgently necessary to remove that risk. This is a narrow exemption and the burden of proving it falls on you afterwards. Photograph everything before work starts and get the tree surgeon's written assessment on record.