A Londoner in Germany
works for a charity in London's Barbican building.
Susan Ranger is one of more than a million people who commute into London by rail every day.
She travels from Thorpe-le-Soken in Essex to the offices of a charity in the Barbican - and pays £4,428 for her season ticket.
It is a journey of just over 70 miles, so we took her to a town the same distance outside Berlin - Jessen on the River Elbe.
She left on the 0643 and, after changing trains a few stops down the line at Lutherstadt Wittenberg, stepped onto the platform at Berlin Hauptbanhof at 0756.
Two minutes late - but she wasn't worried about that.
The single ticket cost 22.10 euros (£15.20) - more than £10 cheaper than the same journey on Susan's normal route.
She rated Deutsche Bahn trains highly for comfort.
"The trains are a lot quieter than in Britain," she said.
"And so smooth - you can really relax. The seats are bigger too."
Transport experts put the difference in price mainly down to different levels of public funding - and the extra pressure on the UK's transport system because Britain is so densely populated.
Anthony Smyth, chief executive of the rail watchdog Passenger Focus, says passengers will judge the cost of their journeys at home in comparison with other European countries.
"The fact is, for many comparable journeys it is cheaper on the passenger.
"We know from our research that many passengers feel they're not getting value for money."
Richard Middleton, the head of rail at the transport analysts Steer Davies Gleave, says the UK is not necessarily getting less for more.
"Passengers are getting a better deal," he says, "but I'm not sure taxpayers are."
"Germany is very good at integration - timetables match up."
"But the UK is better at providing information for passengers."
A Berliner in the UK
is a theatre director and property consultant.
Using public transport in London was a new experience for Calvin McBride.
The theatre director and property consultant uses trains and trams in Berlin every day.
He has lived in the German capital for 10 years.
When he joined Susan for her daily trip to work from Thorpe-le-Soken to central London, he thought the journey was very expensive at £26.10 for a single.
"For around £5 (7 euros) more, I could travel 350km from Hamburg to Berlin, on a high-speed train which has a restaurant car," he said.
He rated the journey reasonably good for comfort and punctuality, but he much preferred German trains.
"The aisles aren't as wide as I'm used to and you feel you're disturbing people when you walk up and down."
After the 80-minute train ride, it was on to the Underground in rush-hour.
Calvin was happy with the conditions on the Circle Line - "not at all the crush I'd been expecting" - but found the Central Line very claustrophobic.
"I've seen public transport as crowded as this in Germany, but only after football matches."
Richard Parry, the director of strategy and service development with London Underground, says that because three million people use the Tube every day some trains will always be crowded.
"But we're not fatalistic about it," he says.
"Investment we're looking to make over the next 10 or 12 years will increase capacity by around 28%."
International travel consultant Jim Steer says the UK has a relatively user-friendly system, but many other countries have newer networks.
"The London Underground map is well known all over the world and the Tube is very easy to get around.
"But, on the other hand, we have old infrastructure and we haven't kept up with the level of investment you saw in Berlin."
Train companies say government money over the next few years will bring improvements in capacity and infrastructure.
But UK passenger groups are warning that government plans to cut rail subsidies from around £4.5bn to £3bn will lead to a rise in fares.