“I said to Simon, ‘Nothing can prepare you for how much you are going to love that child. You will love that child much more than you love yourself.’
"He replied, ‘That’s not possible’.”
The 42-year-old continued: “It is one of those things that when it happens you embrace it. You might think you will be this kind of dad or that kind of dad, but until it happens you don’t know.
“But I know Simon is great with kids. We have a lot on the show and he is superb. He is brilliant at talking to the kids and is very warm with them. I think he will be a great dad and he will really enjoy it.”
David celebrated the birth of his first son Alfred with model wife Lara Stone, 30, last May, so we imagine he knows exactly what he's talking about.
And, with mummies Amanda Holden and Alesha Dixon on the Britain's Got Talent judging panel, Simon has got plenty of parents to turn to if he ever needs advice on nappies, late night feeds or burping!
Simon and Lauren Silverman's baby boy is due this March - we wonder if they really will name it after the X Factor mogul?