Q and A: Modern slavery in the UK

Police are questioning five people over allegations of slavery after 24 people were found allegedly held against their will on a traveller's site. The case is unusual - but is slavery a hidden problem in modern Britain?

What are the facts behind the case in Bedfordshire?

Is this case unusual?

What are the offences at the heart of the investigation?

Why did Parliament need to create anti-slavery powers in 2009?

So what do we know about the numbers?

So it's an immigration problem?

How can slavery exist in a modern society?