Some of the latest pieces of hi-tech kit to help in the fight against illegal immigration are being used by the UK Border Agency at the Eurotunnel terminal just outside Calais in France.
Whether it's as straightforward as scanning a passport or using a microphone so sensitive it can detect a person's heartbeat the team there will use it.
Officials don't give out specific numbers but say they check 35% of all the lorries that go through the terminal.
That helps them catch more than 100 people trying to illegally enter the UK every month.
Ivan Macey runs the operation. He said: "Given the huge amount of traffic that goes through the channel tunnel we can't search every single lorry.
"But we're lucky here. We've got a large number of enthusiastic, committed staff and they'll either use the equipment to decide whether to get inside and check a lorry out or they'll just use their own nous and a hunch."
The kit available at their disposal includes computer checks for passports, ID and travel documents.
It is satisfying when you actually catch them but you do feel a bit sorry for them, especially if there are children involved
There are also carbon dioxide detectors to check for high levels of the gas that everybody breathes out - a high reading is a sure sign there are people in the back of a lorry.
There's also a super-sensitive microphone which is so hi-tech it can even detect a person's heartbeat.
Rachel Bramley is one of the officials who help with the searches.
She said: "Obviously getting within the load, if there're a lot of them, you do get quite a lot of adrenalin because it can be quite scary.
"It is satisfying when you actually catch them but you do feel a bit sorry for them, especially if there are children involved but at the end of the day we're just here to do our job."
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