AGED six months, Katie is beginning to grow up.

Experience with the Other Two reminds me that there are various stages where young children suddenly start to act differently, and yet it still takes you by surprise when it actually happens.

With Katie, it means that she has now finally put the first stage of being a baby behind her, and that's as sad a landmark as it's worth celebrating.

One sign was the way that her eyes burnt into my face as I was driving down the road.

I looked to her car seat to see her staring back, genuinely interested in what was going on.

She's started to grab and grip anything she can get her hands on, and giggles away when you tickle her belly.

Maybe I'm just a proud dad, but I'm also convinced that she tried to make drumming patterns with her arms when we were listening to the Foo Fighters.

The flip-side of that is her rock and roll attitude.

She has now started to wake up at 3.30am, not to be fed, but because she wants to play.

How do I tell her that even her hero Dave Grohl has to get up in the morning?