Thirty-one stowaways had their hopes of entering the UK shattered after border officials found them hidden inside four UK-bound lorries at the Port of Calais.
A sniffer dog indicated there were people inside a Peterborough-bound Turkish-registered lorry and 12 Albanians were found among the cargo.
Officers using heartbeat monitors also discovered six Afghans hidden in a Polish-registered vehicle which was heading to Accrington, Lancashire, with its load of sofas.
A detector dog also led officers to find six Albanians hidden among nappies on a Czech-registered lorry bound for Lincolnshire.
The fourth discovery was in an Irish-registered lorry heading to the Republic of Ireland. A dog led officers to find seven people on board - three from Iran, two from Pakistan, one from Afghanistan and a Syrian.
All the stowaways were handed over to French border police.