It’s half term next week, a fact that, if you’re a breeder, you will already know and if you’re not you’ll soon find out. Because you, the non-parents, will be the ones turning up at the office to find it empty save for the scorch marks left by your colleagues’ feet as they sprinted out of the door on Friday and the pile of extra work — their work — winking at you from your desk.

Then you will glance at the wall-planner and remember that the breeders block-booked this week off back in January as they have done with most of August and Christmas up until 2014, shading in the days with their felt-tip pens, and now you are holding the fort along with the tumbleweed. As usual.

This, at least, is the refrain of my childless friend who is a lovely person but is having unlovely thoughts about some of the parents in her financey-type office whose needs always seem to take precedence over hers. She is starting to tire of always working through the summer, having to take her main holiday in rainy October and spending Boxing Days on the M1 driving back to London with a face like a slapped backside.

You’d never guess that behind her forced smile, as she enthuses over another potty-training anecdote or soothes a colleague’s hysterics over a departing nanny — “She’s pregnant! How could she do this to me?” — that really she’s thinking: “Oh, change the record you self-absorbed loon.”

I’m a parent but as it happens I sympathise wholeheartedly. Not only because I remember, pre-child, what it was like spending all those Christmas Days office-bound, those sunny Bank Holidays eating triangular Esso service station egg sandwiches while imagining smug family rounders games on the heath, but also because I share her view that non-breeders are frequently the forgotten heroes of the workforce.

A new BBC2 series, The Trouble With Working Women, started this week and, like so much of life now, focused largely on the con of “having it all — the problems that mothers suffer trying to balance the demands of work with any semblance of quality parenthood”. It is a massively important subject, obviously, and deserves debate. But guess what? It is not the only important subject. One statistic quoted in the programme is that, by their 40th birthday, more than a quarter of women with university degrees won’t have had children. A fifth of all women born in 1975 and later will remain childless. This is a very significant segment of the labour pool. Perhaps it’s in our interests not to take it for granted and cheese off the childless so royally that they hope we all choke on our sense of entitlement.

Logically, the “child free” should be valuable to employers because, either through choice or bad luck, they never actually got to the point where they could claim maternity pay, time off to nurse a sick kid or leave the office early to make it to nativity plays/swimming galas/open days? But are they? Bizarrely, no.

New research from Lancaster University suggests that women who are seen to have chosen a career over children are more likely to be “vilified” at work by bosses who regard them as “cold and odd”, a description it’s hard to imagine being applied to a man in similar circumstances.

Dr Caroline Gatrell, who spent six years researching women in the workplace, believes such females are eyed suspiciously as “emotionally deficient in an almost dangerous way” and often excluded from promotions that would place them in charge of others (“she’s just not a ‘people person’ ”).

Conversely, those who haven’t had children but are still of an age where they might are overlooked for senior roles just in case they do sprog. How’s that for a lose/lose situation? You’re either an unsafe bet or a dried-up, cold fish.

Surely the unfairest of all the prejudices that women without children must bear is the assumption that all mothers are by definition “warm and caring” and non-mothers aren’t. Adjectives such as “tough, materialistic, self-centred” are liberally applied to the child-free when we all know mothers upon whom that description would fit very comfortably. Being fecund doesn’t mean you are not f***** up: just ask Karen Matthews.

The status of motherhood has been elevated considerably in recent years — a good thing, obviously. But some mothers have seized on this to self-sanctify. They seem to think that they are in permanent domicile on the moral high ground where their needs and prefences must prevail and they milk their belief with all the vigour of a breast pump.

All parents are guilty to a certain extent: enjoying the special treatment that parents get on aircraft; lapping up family tax credit or child benefit which we don’t always strictly need with an air of “because I’m worth it” .

But we all know there’s a particular new breed of martyr who wears her motherhood like a hairshirt, leaping upon any non-parents who might casually remark that they feel a bit tired with: “Tired? Ha! Try wiping up vomit at 3am and doing plaits at 7am, then tell me about tired. I come to work for a break.”

She has the monopoly on everything: fatigue, busyness, stress, hard work — and yet won’t hesitate to tell others that their lives will be meaningless husks if they don’t exactly replicate hers.

Why does she do this? There are plenty of us who love our kids more than life itself but don’t feel the need to go bullying our friends into getting knocked up. It’s not as if she particularly likes other mothers anyway; there’s no sisterhood from her, just a competitive resolve to prove that she is even more self-sacrificial than them because she hasn’t had a facial since March.

Here’s a way for non-breeders to make the martyr mother put a sock in it. Next time you’re dashing off to commence another working Bank Holiday and you come across her hammering nails into her imaginary cross, ask her if, for a single moment, she would want to swap places. Then watch those tired legs run.

Times Recommends

• It’s not just about Iraq, it’s about Blair’s style
• You can’t rank hospitals like football teams
• Minarets are not an essential part of Islam