Sam Mendes says directing a James Bond movie is a ''lifestyle choice''.

The 49-year-old filmmaker - who is currently at the helm of the franchise's latest instalment 'Spectre' - has insisted he has no plans to direct the movie's sequel.

Speaking of the ''enormous undertaking'' that is a Bond movie, he shared: ''I don't think I could go down that road again. You do have to put everything else on hold. [It] really is more a lifestyle choice than a job.

''This is a bigger movie than 'Skyfall'. It's shot in more places - we were in Mexico City and Tangiers and northern Sahara and Rome and the Alps and London.''

Sam also revealed the film's title song had been finished and insisted fans wouldn't have to ''wait long'' to hear the track.

He told BBC Radio's Test Match Special: ''I can say that the song's been recorded and it's fantastic and I'm very excited about it. You won't have to wait long.''

Meanwhile, 'Lay Me Down' hitmaker Sam Smith - who was once rumoured to have been given the honour of recording the track - has insisted it ''definitely'' won't be him.

He said: ''It's definitely not me. People seem to think I'm doing it but I have no idea what's going on. I heard Ellie Goulding was going to do it, it's definitely not me.

''I would do it if I was asked. I would do it in a heartbeat. And I could do it and it would be great, but I'm not a star and for that you have to be a big star. You have to be someone in America.''