Though I doubt the scientific basis to this statement, I have long held a theory that there is a direct correlation between the amount of fun had by children over a weekend and the colour of the bath water on a Sunday night.

I might go so far as to propose that the correlation may well extend to everyday life. Being the parent of three perma-filthy children is nothing to be proud of but it is certainly a marker of the amount of time spent outside diving for footballs, climbing trees and all round general dirt-generating activities, and hopefully an indicator of their happy carefree attitude to life.

This week we reach a milestone in the family: our eldest son, Will, leaves primary school. I know from experience how much responsibility comes from being the first born; always being the first to push the boundaries and venture into new things and now I get to experience it from the other side of the fence and let me tell you, it’s a whole lot harder from this side.

For the past 11 years we have charted his every achievement, revelled in his successes and encouraged him when he’s found things tough.

It’s only when we became parents that I completely understood the absolute unswerving, unconditional love you have for your children. We’ve watched him, as all parents do, turn into a son we are truly proud of.

He may not have set the world alight quite yet and his starring role as a fork in his last school play was maybe not quite worthy of an Academy Award, but he was the smiliest, happiest and proudest looking fork I’ve ever seen and that means more to me. He has always been his own person, something I deeply admire.

When other boys became obsessed with sport, he was happy to hang back and try other things as well. Rarely the ringleader but a quiet, unassuming and caring boy not afraid to swim against the tide and always the first to stick up for his friends and never embarrassed to be seen showing affection to us.

For the first time last week, as he was walking through town holding my hand, at the sight of two very pretty teenage girls, I was rather abruptly shaken off.

I felt the pang of a parent about to play second fiddle to friends and especially girls!

There is a sense of irony in building up a child to be prepared for the world and then watching as you get left behind after being his one and only.

His last day of primary school will be emotional, though I suspect more for me than him.

He’s ready to go, he needs more and he’s looking forward to the challenges that a new school brings.

For me it’s the end of lazy walks to his lovely tiny primary school holding his hand, knowing all of his friends and their parents and being able to be part of his everyday life. Also an abrupt reminder that I am now old enough to have a son in secondary school, which I’m sure can’t be right?

Until the beginning of September, when our boy becomes a little less of the innocent child, we’ll be encouraging him to keep his knees as grubby as possible. We’ve planned a summer of camping, den building, family football matches and laughing at how he burps the alphabet.

He’s got so much ahead of him, we’ll be clinging onto his childhood until the last possible moment. At some stage, I’ll need to be completely clear with him about the viability of Father Christmas so he doesn’t start writing letters to Santa in his first term of high school.

How can it be that a child has had the sex education talk yet still pretends to believe in the tooth fairy?

But for now, I’m savouring every moment with him. There’ll be tears on his last day I can guarantee, but by the time we’re experiencing this for the third time, I think we may feel a little less nostalgic. I guess it’s the first born advantage.

Let mud reign supreme and their lives be forever filled with enjoyment.

That’s unless they choose a career in dentistry...