Paramedics treated 23 passengers on board (Pic: Rhein-Hunsrueck Anzeiger)
Eight elderly British tourists are being kept in a German hospital after being struck down by a serious gastric illness during a Rhine cruise.
The rest of the 100 or so passengers aboard the Lady Anne are returning home, accompanied by a doctor.
The ship has been moored at Boppard since Monday's sickness and diarrhoea outbreak, caused by the norovirus which is dangerous for the very young or old.
Operator The River Cruise Line said all passengers would be fully refunded.
The Leicestershire-based company has now admitted passengers on a previous cruise had been affected by an "undiagnosed illness", after one of them told the BBC at least 18 people had suffered similar symptoms.
In total, 20 people from the most recent cruise were taken to hospitals in Boppard in western Germany and eight were deemed too ill to return to the UK on Wednesday.
They will be assessed by doctors before being allowed to return home.
The rest of the passengers have now been allowed to leave the Lady Anne and will return home via Folkestone.
Twenty-three had been confined to their cabins, where they received treatment from paramedics, while the remainder stayed in the on-board lounge.
The norovirus can cause a fever, headaches and aching limbs but most people make a full recovery within 48 hours.
However, the very old and very young risk becoming dehydrated which may require hospital treatment.
A German health official said many of the holidaymakers were at least 70 years old.
The Britons had been on a five-day cruise along one of the most picturesque stretches of the Rhine valley in Germany.
Apologies to passengers
The Lady Anne will be professionally cleaned to ensure the safety of future passengers, The River Cruise Line has said.
Its next scheduled cruise has been cancelled and all staff and crew will be changed before it sails again.
In a statement, the company said: "Our passengers, crew and staff who are on board the Lady Anne are now able to get off the ship and doctors have confirmed that they are fit to travel and we are making arrangements for them to return home today.
"We will be arranging for a doctor to accompany our passengers during the journey to Folkestone.
"We would like to again express our gratitude for the excellent work of the German paramedics and offer our apologies to all those directly and indirectly affected."
However, Derrick Dimmock, 73, from Luton, said 18 members of the 24-strong group from his community centre had taken ill during a trip which began on 14 November.
He said: "People were taken ill over the five days. I got sickness and diarrhoea at 10.30am on the Sunday and I was up by 10am the next day but I couldn't eat for the rest of the holiday."
The company statement said the cause of the "undiagnosed illness" was not identified until this Monday, 24 November and that the vessel was cleaned afterwards.
The kitchen had been inspected by relevant authorities and nothing untoward was found. Staff have since kept in regular contact with those affected, it added.