Trespass alone is a matter of civil law, which means that the police have no power to arrest you for it; police may nonetheless help landowners remove trespassers from land.
Trespass is entering – or putting property on – land that belongs to someone else, without their permission.
If you have ‘implied permission’ to enter somewhere – for instance a shop open to members of the public – then you are not committing trespass until you have been asked to leave by the owner of the building or their representative. In a shop this is often a manager, but should not be a police officer. If you fail to do so, then you could be taken to a civil court (‘sued’) by the owner.
Aggravated trespass is a criminal offence, so you can be arrested for it.
You must be doing two things to commit aggravated trespass:
2. Intentionally obstructing, disrupting, or intimidating others from carrying out ‘lawful activities’.
Further to this, a senior police officer has the power to order any person believed to be involved in aggravated trespass to leave the land; if they refuse to leave after being ordered to by police officer, or if they return to the land in question within a period of three months, this is an additional offence.
Sentencing starting point:really varies dependent on who you are and where you were, from conditional discharge to suspended sentence. Maximum penalty is 3 months imprisonment, or a fine of £2500, or both. First time offenders would likely get a fine of between £200 – £300.