United Kingdom, April 9 -- Peter Capaldi has started to worry about getting older since becoming a grandfather.

The former 'Doctor Who' star - who turns 67 on April 14 - adores his grandchildren but they have made him think about the "ticking clock" of ageing and he now fears he won't get to spend enough time with them.

He told the Guardian newspaper: "I'm a grandparent now so suddenly I have babies and lullabies in my life again. It's wonderful, but being Scottish there's always a melancholic streak in me that will seek out the bleak thing about it.

"In this case it's the ticking clock. These fabulous children bring all this vigour and chaos into your life, but how long do you have left to spend with them.

"That made me think of the ...