The classic steam train was packed with enthusiasts and local dignitaries for the relaunching of Mid-Hants Railway's Watercress Line.
The event was held following the completion of works to rebuild nearby White Lane Down Bridge on the line which runs from Alresford to Alton.
Mr Titchmarsh said: ‘It's the most wonderful timewarp, you come over the bridge to the Watercress Line and you are back in your childhood.
‘The wonderful thing about locomotives like Flying Scotsman is they breathe, they are living, she's panting, just waiting to get back to Alresford.
‘What an enormous honour it is for me, a life-long steam engine fanatic, to be able to be here today.’
Watercress Line director Simon Baggott said: ‘It was a landmark moment as Flying Scotsman travelled across the new White Lane Down Bridge, surrounded by 300 local school children waving flags before arriving into Alton Station and breaking a banner to officially reopen the line.’
The historic train will be back on the Watercress Line later this month with rail enthusiasts able to get a seat on board.
Services will run between Saturday February 29 and Sunday March 8 between Alresford and Alton.
Flying Scotsman cost £7,944 to build in 1923 and it became the first locomotive to reach 100mph before British Railways withdrew the locomotive from service in 1963.
It was purchased by the National Railway Museum in 2004 and was restored with £4.2 million from the National Heritage Memorial Fund, the Heritage Lottery Fund as well as from public donations.