It’s a killer, realising that the kids are moving away from you, that you are no longer indispensable to them. But maybe maturity, as a parent, lies in accepting this is a cause for celebration as much as for sadness.

In October, having climbed one of the towers of Suffolk’s Framlingham Castle with my eldest boys Ethan and Ripley, I stepped out onto the narrow walkway leading around the top of the 13-metre-high curtain walls and felt my legs turn to jelly under me. At first I put it down to panic that Ripley, the middle boy, has always suffered from severe vertigo – to the point of actually screaming in aeroplanes or when walking on floors so highly polished they look like glass built over empty space. But once Ripley had reassured me that, for the first time in a situation involving heights, he was actually fine, it was up to me to face my own fears and phobias.

For a few seconds I stood, heart hammering, breath ragged, telling the boys that there was no way we could go round, that Mummy simply couldn’t do it. The trouble was, we were part-way through a Halloween trail of the 12th-century castle, and some of the remaining clues were dotted around the walkway. Looking at the boys’ desperate faces, I felt like an abject failure.

Finally, unwilling to give up, they told me they’d do the walkway by themselves. I looked at them, seven and five-and-a-half, newly fearless, and while I knew they could do it – sturdy metal barriers meant there was no danger of falling – I realised that watching them complete the circuit without me would actually be more painful for me than forcing myself to do it. It would mean conceding that they didn’t need me any more – admitting it both to myself and to them.

Telling myself that I couldn’t let them go in case Ripley did freak out part of the way round, I forced myself to put one foot in front of the other and follow them around the ramparts, not looking down and not enjoying the views over the surrounding countryside, which are said to be stunning. The boys were completely unfazed, prancing along looking for the pumpkin buckets containing clues that would ensure them a prize in the gift shop, not even slowing down at the wooden plank bridges through the towers, passing over hellish sheer drops…

I was proud for my five-year-old at having gone beyond his fear of heights, and embarrassed that my own, if anything, seemed to have worsened – other visitors we met on the way round noticed how I was grasping the railings idiotically, my jaw clenched. Of course, there’s nothing a mother can’t or won’t do for the love of her children, and 15 minutes of wobbly legs, a dry throat and a racing heart walking around a castle ramparts is no great shakes, if you’ll pardon the pun. But over and above all heroics and sacrifices, surely one of the hardest parts of being a parent is knowing when to set them free. Up on the wall-walk, I learned that even as I clung on for dear life, I had to let go.