Q&A: Brodie Clark and the UKBA border checks row

Brodie Clark is alleged to have authorised officials to abandon biometric checks on some occasions

The row over claims that UK border controls were relaxed without ministerial agreement continues to rumble on, with ex-border force chief Brodie Clark insisting he is "no rogue officer".

Home Secretary Theresa May, however, has insisted he acted without her authority.

Labour have called the affair a "fiasco" and demanded to know whether anyone posing a risk to national security was allowed to enter the UK as a result.

So what is the background to the furore?

What has happened?

What happens at the border?

So what exactly happened?

So Brodie Clark exceeded his authority?

What's Brodie Clark's defence?

What's the problem with this explanation?

So who's right?

Where does this leave the investigation?

What are biometric chips?

Have border guards dropped checks before?

Was the pilot a success?

What do staff say?

Do these checks really work?