How to plan a successful jailbreak

Last week two prisoners made a daring escape from a Greek prison by helicopter - their second airborne jailbreak.

Convicted drug trafficker David McMillan, who spent two years plotting his escape from a Bangkok jail in 1996, told the BBC how much planning this kind of operation takes.

I had been planning [my escape] from the moment four policeman came into a travel agency and arrested me in Chinatown, in Bangkok.

A local resident captured part of the Greek escape on video

As soon as I actually got to the prison about a week later I started looking at bars and walls and electric fences and I began looking for the best place to be. I went to building six simply because it had the thinnest bars in the windows...

There were not a lot of prison guards per prisoner. Probably one prison guard to 120 prisoners. So it was really run by the trustees, who had their own little uniforms with epaulettes and aviators' wings and things like that.

The entire essence of [the escape] was secrecy. No-one in there was capable of keeping a secret I would say...

Planning is everything

The first thing to do was to get what you could call a private cell.

Most of the cells would be the size of a family garage and had 25 people in them, often sleeping like sardines packed into a tin, literally.

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And if they had chains on, which everybody did, there would be the rattling of the chains, lights would be left on all night.

I paid for a light switch which was another little luxury.

It sounds like I was doing a lot of paying, I mean I had an office, a cook and a cleaner and that kind of thing, but it's not an awful lot of money - for