A Sudanese national has been charged after allegedly walking nearly the full 50.5 km (31-mile) length of the Channel Tunnel towards the UK.
The man was arrested close to the Folkestone exit on Tuesday, apparently after 11 hours inside the tunnel.
Abdul Rahman Haroun was charged with causing an obstruction to an engine or carriage using the railway and remanded in custody by Medway magistrates.
On Friday, David Cameron said progress was being made on tunnel security.
'More sniffer dogs'
"We have done a lot in recent days to improve the situation but there's a lot more to do," the prime minister said during a visit to Betws-y-Coed in Conwy.
"So we've got more fencing, we've got more police officers, more sniffer dogs, more guards, better security and we're making progress.
"Myself and the team of ministers I've put in place, we will oversee these improvements and they will take place in the coming weeks and days."
Mr Haroun, 40, is due to appear at Canterbury Crown Court on 24 August to face the obstruction charge, which comes under the Malicious Damage Act 1861.
There were about 550 attempts by migrants to enter the terminal at Coquelles overnight on Thursday, according to Eurotunnel.
A spokesman for the rail operator said police removed about 200 people from the site during the night.
There were about 600 attempts to enter the tunnel on Tuesday and 400 a night on Tuesday and Wednesday, according to Eurotunnel.
It said additional efforts to secure the French terminal were almost complete and attempted intrusions by migrants were now being brought under control.
There have been thousands of attempts to access the terminal at Coquelles in recent weeks, with nine people killed trying to get into the tunnel since June.
Foreign Secretary Philip Hammond said 100 more guards would be deployed in the Eurotunnel terminal, following a meeting of the government's emergency Cobra committee on Monday.
He also announced a "much improved level of co-operation and collaboration with Eurotunnel" and a UK Border Force and French police presence in the Eurotunnel control room at Coquelles.
It is estimated there are some 3,000 migrants in the Calais area and many are continuing their attempts to reach the UK by crossing the Channel.
Some try to stow away on lorries headed for the Eurotunnel, or climb or cut security fences to try to hide on Eurotunnel shuttles.
Meanwhile, the BBC has confirmed a migrant camp in Calais will feature in an upcoming edition of the programme Songs of Praise.