ACOTR Dan Stevens has revealed the biggest challenge of filming his role as Lancelot in Night At The Museum: Secret Of The Tomb - the heavy armour gave him a bad back.

The former Downton Abbey star joined the cast for the third museum film starring as a Knight of the Round Table helping the regular characters on their quest to save the magic of the Tablet of Ahkmenrah.

Stevens said he was excited about his costume for the role - before realising it weighed 50lb.