Robin Hadley became an angry and discontented person in his early 30s, for reasons he couldn’t then understand.

He was doing well at work and had friends, but there was a feeling that his life was incomplete. ‘Then my best friend told me his wife was pregnant,’ he says, ‘and I felt incredibly jealous.

‘You don’t think of men getting broody, but that’s exactly what was happening to me. I was watching my friends start their own families and thinking: why should they have everything I’ve always wanted?’

Robin is now 57, happily married but still childless, and one of Britain’s only professional experts on male involuntary childlessness — where men are childless not through choice but circumstance.

Sheridan Voysey (pictured) , 45, was diagnosed as infertile. He spoke out alongside other men about the longing for a baby

It’s a subject we rarely broach. Although we often hear about the 20 per cent of women over 43 who are childless, the voices of men in the same position are rarely, if ever, heard.

‘It’s never spoken about, written about, studied,’ says Robin. ‘Men like me, who want to be dads but aren’t, are invisible. People don’t always realise that the pain of not having a child can affect men, too.’

Part of the issue is men do not like talking about it — many fear being judged as ‘weak’, or ‘feminine’, especially by other men.

‘Although men don’t have a biological clock in the same way women do,’ says Robin, ‘they have what I’d call a “social clock”.

‘Famous men who have children very late — Rod Stewart or Ronnie Wood or Billy Joel — really don’t represent the majority: male fertility declines sharply with age and ordinary people don’t have the financial resources a pop star has to go towards childcare at that stage in life’.

But surely men, unlike most women, can easily have a child in their 50s? ‘Many men see their early 50s as the cut off point,’ says Robin. ‘They feel uncomfortable with the idea of being an “old” father.’

Recent advances in fertility treatment have allowed single women whose fertility window is closing to go it alone using donor sperm — a relatively cheap, widely available and increasingly socially acceptable process. Single men, however, do not have that choice.

Robin Hadley (pictured with his wife Maryan) became childless as a result of his wife's inability to have children

Robin says he became childless-not-by-choice when, at 37, he fell in love with a woman who couldn’t have children — his now wife. Robin made a difficult decision: ‘If you love someone enough to marry them…you can’t just switch that emotion off, go away and hope you find someone more suitable.’

Letting go of an imagined family often requires a process of grieving, yet articulating those feelings are difficult for many men.

‘Ask a man to talk to you about not having children and usually he’ll draw a blank. It’s like there’s a huge inferno of feelings pushed down inside of us and sealed with a concrete slab.’

Incredibly, the Office for National Statistics doesn’t collect statistics on how many men are childless —when a birth is registered, only the mother’s fertility history is recorded. The only rough estimate we have suggests that 25 per cent of men over 43 are childless.

Fatherhood can be the definition of your whole identity and you’re thinking, There’s a feeling that it inherently proves you as a real man and so if you’re infertile you must be weak or dysfunctional- Sheridan Voysey

One such man is Andrew Currie, 62. He says he drifted into being childless: ‘My last serious relationship was 17 years ago and, I know it sounds strange, but she and I never discussed being parents. I never thought ahead to where I am now, in my 60s, without children. I wish I’d asked myself when I was younger, “What do you want?” I wish I had said to myself: “Be selfish. If you want children, do it.” ’

Like most men in his position, Currie finds other people’s perceptions of childless men painful. ‘We are seen as suspicious, not to be trusted,’ he says. ‘I understand that’s just the way it is, but it’s a horrible feeling.’

The received wisdom, of course, is that men can pick and choose if and when they want children. But a new study among couples undergoing IVF treatment confirmed that men, just like women, risk leaving fatherhood too late, with a fall-off in fertility in some men over the age of 40.

Sheridan Voysey, 45, a broadcaster and writer, and his wife, Merryn, began trying for children shortly after they married two decades ago. The couple spent huge sums of money on alternative fertility ‘cures’ before Sheridan was diagnosed as infertile.

Sheridan (pictured right with his wife Merryn) believes fertility treatment can be the making of you as trying makes relationship bonds stronger

He describes involuntary childlessness as ‘a grief without a death’, adding: ‘The little “us” you’ve dreamed of is never going to exist.’ Men need more support than they’re currently getting in dealing with childlessness, he says, while also stressing the importance of both grieving and acceptance.

‘If you don’t draw a line under it, the burden of hope can be the unravelling of you,’ he says. ‘Fatherhood can be the definition of your whole identity and you’re thinking, “I am the guy who can’t father a child.” There’s a feeling that it inherently proves you as a real man and so if you’re infertile you must be weak or dysfunctional.’

Part of the problem is that men feel pushed away by friends who have children, he says. ‘I’m a great believer that childless men become great uncles, mentors. We’re a caring bunch. There is a place for us.’

There are dozens of reasons why, despite his best wishes, a man might end up childless.

‘You might not feel financially ready,’ says Robin Hadley. ‘Or perhaps you’re shy and have difficulty making relationships. There’s your choice of partner, and the timing of it. Then there are older gay men; laws regarding marriage and adoption for gay men only changed very recently, so it’s too late for many of them.’

National Statistics estimate around 25 per cent of men over 43 are childless (file image)

Alan Nichols is 53 and divorced. He married when he was 34. Not long after, his wife suffered an ectopic pregnancy and almost died, and when doctors later confirmed she would be unable to have children, ‘she became very insecure that I’d leave her’.

‘But I married her because I wanted to spend my life with her,’ he says. The couple eventually divorced when Alan’s wife had an affair. Single again in his mid 40s, Alan found that the eligible women he met ‘mostly already had kids’. ‘The last thing they want to do is have another baby,’ he says.

Now, as a childless man in his 50s, he finds dating in general a puzzling experience. ‘Women can be very suspicious of men without children,’ he says. ‘I’ve been on dates and it’s literally, “What’s wrong with you, why don’t you have kids?” I find it very insensitive and stupid.’ At 53, he now feels he’s left it too late.

It’s striking, however, how radically many of the men I talked to changed their lives once they had accepted the reality of their situation. Robin changed careers to become an academic, and Alan ‘is excited about the future’.

After a period of grieving, Sheridan now goes as far as saying: ‘Infertility can be the making of you.’ Though failed fertility treatment can put a fatal strain on relationships, ‘if you survive it together, your bond can be even stronger’.

‘I still regret not being a dad,’ says Robin, but he’s no longer ashamed of it. ‘I think men like me want to be heard. We’re saying: “I’m missing out and I think I have something to give.” ’