After seeing a thread on here that I read with interest (and confusion) I am wondering if someone who knows more about the law, can confirm what 'theft' actually is?
The thread was on about whether someone's cat can be stolen. The answer from most people was 'of course it can.' Because it's a possession that belongs to someone, and is registered to them; and many searches on the internet showed this to be true, including one someone posted on page 8 of that thread
@Iris65
www.pets4homes.co.uk/pet-advice/your-pets-and-the-law.html
That makes it quite clear you can indeed steal someone's cat, and it is 'theft.'
Yet someone else said if they just feed the cat, and pet it, and it 'chooses them,' then they are not stealing it. 
They also posted something from the 'Theft' act.
sixthformlaw.info/01_modules/mod3a/3_60_propety_offences/01_theft.htm
Which basically states that taking something is not theft if you did not intend to keep the item permanently, and intended to give the item back.
So surely if that is the case, we can all take stuff, from friends, and neighbours, and colleagues, and our employers, and shops and stores, and say that we didn't intend to keep it, so it's not stealing. And if they can't prove otherwise, we won't get charged with theft surely? Hey Mr Jones, yeah I took your lawnmower 3 weeks ago, but it's only in my garage and I was going to bring it back.' 'Hey Mr policeman, I took the dress from H & M, but I only wanted it for a few days, so I have something to wear for the party. I was going to bring it back!'
How can anyone prove I intended to keep the item permanently?
And if they can't, then surely it's not theft? That is what that link to the theft act is inferring.
Enlighten me someone. I am confused by all these grey areas!