Smith will play the Doctor alongside Elisabeth Sladen (Sarah Jane) and Katy Manning (Jo Grant) in the Doctor Who spinoff.
He told SFX: "I did feel I was in the presence of Doctor Who royalty! Both [Elizabeth and Katy] go back a long way and occasionally I'd be reminded of the show's long and glorious past."
He added: "You never lose sight of the fact that you're part of a programme which has been around for a very long time and will doubtless go on for a very long time in the future, long after I've stopped playing the Doctor."
The actor also revealed details of his role in 'Death of the Doctor'.
"There are rumours of the Doctor's demise, which obviously cause Sarah Jane a great deal of concern and an understandable need to try to help by rushing to his side," he explained. "It's drama on a grand scale, with some tense scenes inside a secret base beneath Mount Snowdon."
The Sarah Jane Adventures will return to BBC One next month.