kent police
The officer, a probationary constable, was guarding a cordon as disappearance was investigated.
Footage from Dover shows dozens of drivers surrounding officers as they face having to wait days to cross the Channel.
Some 650 lorries are currently stuck on the M20, and a further 873 moved to an airfield, as the government scrambles to reopen travel in and out of the UK.
Activists behind the stunt said police had "better things to be doing with their valuable time" ahead of potential traffic chaos post-Brexit.
One man had gone missing from a tanker ship anchored off Margate.
Press reports have named the men as twin brothers Billy and Joe Smith, who appeared on the TV show My Big Fat Gypsy Wedding.
Discovery follows 39 dead bodies being found in a lorry container in Essex.
The six-year-old fell into water in Sandwich on Saturday afternoon.
Kent Police said officers were called to Richborough Road in Sandwich.
They were discovered on the motorway near Sevenoaks, Kent.