21 May 2016 Last updated at 13:55 BST
The special train's run saw it steam through the Thames Valley to Salisbury, it was then due to make a round-trip via Southampton to Salisbury, then back to London.
British Transport Police (BTP) have urged the public to stay back from the railway.
Earlier this year, dozens of other services were delayed by people encroaching on to the track when the famous engine travelled from London to York.
One of the world's best known steam locomotives - the Flying Scotsman - is making a tour from London to the south coast.