How to survive being a new dad
Like Prime Minister David Cameron, Stuart Derrick at 43 years of age is not a novice when it comes to looking after children.
He and his wife already have a son aged three. A few months ago, they had their second child - another son.
Stuart's recently-written advice booklets for the National Childbirth Trust aim to help other new fathers adjust to their role.
But despite his experience, Stuart says it is still a shock to be thrown back into caring for a newborn baby.
"You tend to forget just how hard it is. I presumed that as a second-time dad it would be a walk in the park.
"The biggest surprises were the obvious things - the lack of sleep and the sheer exhaustion, plus all the crying.
"If you have a crying baby you go through all of the obvious things on your mental checklist. Are they hungry? Is their nappy wet? Is it wind?
"But sometimes nothing works and that's the particularly tough bit about it. A lot of parents struggle with that."
But, he says, for men it's the emotional side of things that's hardest.
"Procedural things like changing a nappy or making a meal are easy to understand. But saying the right thing is trickier."
Stuart describes a mixture of guilt and relief about returning to work and leaving his wife at home to look after the children.
"You feel torn about leaving. You know you need the money and have to go to work and, if you are honest, you are glad to step away from the chaos for a bit.
"But you have a guilty sense of escape. And you know that as soon as you come home you will be straight back into it - your second job.
"You don't want to make too much of the 'poor daddy' bit to your partner. She's the one doing the bulk of the work. But you are exhausted."
He says the first time round he tried to do everything by the book to be a supportive husband and hands-on dad.
"With our first son, Jamie, I felt I had to do more of my share in the night. My wife was breastfeeding so I would get her a glass of water and change his nappy if he needed it.
"But mostly I would lie awake trying to be silently supportive, yet the best thing I could have done would have been to get my head down and get some sleep.
"There will be plenty of other times when you can help and there is no sense in both of you being tired."
Dr Ian Banks, who is a father of four and president of the Men's Health Forum, agrees with this advice.
"It is worth doing it like a rota and taking it in turns so that you both get a break from time to time.
"The sleep deprivation you get with a newborn takes its toll. It affects your work, your relationship and your driving, which is worth remembering."
Dr Banks says his own motto is "when all else fails, read the instructions".
He's written a baby manual for new dads in the same style as the Haynes series of car repair manuals.
As well as giving practical tips and step-by-step instructions, including how to change a nappy, the book also touches on the emotional side, explaining how to spot post-natal depression in yourself or your partner.
"Men like to be in control, but when they have a baby it's hard to be. If they can feel prepared, that helps. That's what the manual's for."