Travel from Southampton to London

Buy a Southampton - London train ticket. There is no advantage in buying ahead of time, so buy it from the station ticket machine. It will be about £30. Instead of taking the direct London trains (xx00, xx25, xx30, xx55 past the hour), take the Crosscountry service towards Birmingham (xx15 and some hours at xx45. Alight at Reading, then take any train direct to Paddington. Despite having to change, this route takes about the same amount of time as the main Waterloo route, but you'll end up at Paddington. It's a 'valid route' on your ticket and will take about 1h10. Mark

Mark has given you the most convenient route (Southampton-Reading-Paddington). This will work well for someone schlepping a large suitcase. The walk-up fare is £36.50. Trains from Southampton to Waterloo run more frequently than those from Southampton to Reading. Booked well in advance, you can get a Megatrain ticket from Southampton to Waterloo for as little as £1.00. However, those tickets aren't offered on morning trains. The any time of the day walk-up fare is £36.50. You can take the Tube (Bakerloo Line) directly from Waterloo to Paddington.

Mark, tagging on to John's question, can you recommend the most convenient route for my wife and me from Southampton (off a ship) to St Pancras (Eurostar)? Thanks.

Will: the best way to St Pancras is to take the South West Trains services from Southampton to Waterloo. These depart four times an hour, but note that the fast trains are xx00 and xx30. You'll get to Waterloo in about 1h10 and it's about £30 each. As Tim said, you could probably get cheaper (but slower) tickets on megatrain.com, but note that you can only take the train marked on your ticket; try and get any other one and you'll have to buy a brand new ticket. From Waterloo you have a number of options, but a taxi is probably the easiest to St. Pancras, and should be less than £10, taking about 20 minutes. You could also take the tube or catch a bus, but I don't think there's much benefit in that if you're just getting straight on a train to the Continent. You could also follow my advice to John and go into Paddington, from where there is an easy tube connection to Kings Cross by Hammersmith & City or Metropolitan line, but the trains are less frequent to Paddington.

Will, A Tube ride from Waterloo to King's Cross/St Pancras will take 15 minutes. Take the Bakerloo Line from Waterloo to Oxford Circus and the Victoria Line from there to King's Cross/St Pancras.

Mark and Tim ... thanks! To the point and very clear.

You're welcome, Will. Since Mark mentioned the bus, I'll give you the details. Bus 59 goes directly from Waterloo to St Pancras. The Transport for London Journey Planner says that buses run every 6 minutes and the ride takes 30 minutes. If you take the bus, you won't have to haul luggage up and down stairs at the Tube stations. And a single bus ride costs less than a single Tube ride.