People are not having their dogs prperly wormed on their return to the UK
Echinococcus multilocularis (spread by dogs and foxes)

The tapeworm Echinococcus multilocularis is found all over most of Europe and in other foreign countries. Foxes, and domestic dogs are the natural hosts for the adult stage of this tapeworm. The adult tapeworm lives in the gut of the dog, fox or other members of the dog family. The head of the tapeworm attaches to the gut wall and then produces hundreds of eggs that are shed in the dog's faeces, Wild rodents such as mice serve as the intermediate host. Eggs swallowed by rodents develop in the liver, lungs and other organs to form multiple cysts and infect dogs and foxes. People can become an intermediate host by handling infected animals and can be infected by swallowing the tapeworm eggs. The disease can be very serious in people.

Prevention - worming & hygiene

Worming regularly with a product with suitable tapeworm activity will reduce the risk of Echinococcus multilocularis infection in your dog when abroad.
You will need to follow the rules of the new Pet Travel Scheme and have your dog treated by a vet for Echinococcus multilocularis before returning.
Don't allow your dog to wander freely and eat rodents when on holiday.
After handling your dog, always wash your hands with soap and warm water.
Talk to your vet well before you intend to travel to ensure all the appropriate paper work and processes are followed to allow your pet to travel with you.

Apparently, dog smuggling from the EU eastern block is common,
I think there was a "Watchdog" programme on the subject.
Vets say the returning dogs are often not given time for the drugs
to work before the dog is back in the UK.

We have found the regulations just as strong when we brought our dog back into the UK.
We have to find a vet 24 hours before departing and have the dog checked over to see it is fit to travel and is not carrying any ticks or other parasite, the vet then administers the worming tablet and then date and time stamps as well as signing your dog passport. You cannot depart then until after 1 day and before 5 days of seeing the vet. The vet on our last visit gave us a tablet to give to the dog 3 months later to complete the treatment.

the passport is checked along with the dogs micro chip to confirm it is the same dog when we check in, so if you follow the procedures correctly there should be no problem about bring the tapeworms into the UK. One time when checking in on our return to the UK we where behind one of these dog transporters who 12 dog in two vans to check in, and they could not find the chip one one of the dogs, these micro chips can migrate around the dog and can be difficult to find some times, we eventually managed to get checked in, but normally it is a simple process.

When in France we always keep the dog on the lead and try to control here around other dogs, if you have spent 2 o 3 hours looking for a dog in the undergrowth you learn to keep a close eye on her.

It is always the people who follow the rules who get penalised by the actions of the few who ignore them, what about all the irresponsible dog owners in the UK who do not clean up after their dogs and probably never worm their dogs anyway, there is still an infection from round worms that can blind children.

I think you will find it difficult to get back into the UK with your pet unless you conform to the strick regulations to be found here:-

https://www.gov.uk/pet-travel-informatio...ners#blood-test

Only illegal dog owners are risking the import of Fox Tape Worms and other infections.