"Breaking and entering" it's a criminal offence, and walking through an unlocked front door back door doesn't count. If you are on someone's land but didn't have to break in then that's trespass, which is just a civil offense.
Theft is a crime in any case (indeed even if you're not on their land e.g. snatching a phone off the street).
Yes there is:
https://www.legislation.gov.uk/ukpga/1968/60/section/9
https://www.college.police.uk/guidance/residential-burglary/...
> "Breaking and entering" it's a criminal offence, and walking through an unlocked front door back door doesn't count.
No breaking and entering is known as burglary. Also if you walk through the front door with the intent to commit a crime it is still burglary. The important part is trespassing with the intent to commit a crime.
See https://www.legislation.gov.uk/ukpga/1968/60/section/9 and https://www.cps.gov.uk/prosecution-guidance/theft-act-offenc...
Burglary is defined in the Theft Act 1968:
https://www.legislation.gov.uk/ukpga/1968/60/section/9
The door can be wide open. The important parts are you are trespassing with the intent to commit a crime.