Dublin is the capital of Southern Ireland. It is not the part of United Kingdom. But the trade and travel between the two is smooth and tourist smoothly can travel between these destinations. The distance from Dublin to London is 365 miles approx. you can travel from Dublin to London by train and air. The best way to travel from Dublin to London would be by Air, as you can take a direct flight from Dublin Airport to London Heathrow. Dublin airport is also the top 10 busiest airport of Europe. You can get flights from Dublin to London for as low as € 100 Euros. The best and most affordable service is provided by Air Lingus Airlines. Another good budget airline is Ryanair which runs its flights on to London Gatwick, Stansted and Luton Airport. If you are planning to take a flight from Dublin to London Heathrow, there are only two airlines which are offering the flights which are Air Lingus and British Airways. The time taken for Dublin to London flights is about less then 1 hour and 30 mins, depending on to which London airport you are planning to go.
Dublin Airport Terminal 2
Air Lingus Plane at Dublin Airport
Another way of travelling from Dublin to London is by train. The best service is offered by Virgin trains which operates from Dublin port (Irish Ferries) and Dublin Port (Stena). Even though this option of travelling is available from Dublin to London, but this mode of transport does take quite a lot of time, as compared to Dublin to London by flight. The journey duration from Dublin to London Kings Cross station is about whopping 12 hours and 7 hours 30 mins while coming back from London to Dublin. The journey includes 2 changes while coming to London and 3 changes while going back to Dublin. The journey on the most economical side will cost you about € 107 which is rather dearer then travelling from Dublin to London by flight. So I would thoroughly recommend to take the air transport.