A grieving widow has spoken of the moment her husband died from a heart condition while they were having sex.

Lucie Brownlee found herself widowed at the age of just 36 following Mark Johnston’s death, The Daily Mail reports.

The couple had been trying for a baby and were having sex at a time they had identified as the optimum to conceive.

However, the intelligence analyst suffered a catastrophic arrhythmia and could not be revived.

An arrhythmia is an irregular or abnormal heartbeat. Men aged between 35 and 45 are most at risk. 

According to Ms Brownlee, her husband's last words were: 'You’ve still got your socks on.'

Mr Johnston, who was just 37 when he died, had collapsed four years prior to his death and medics discovered that his aorta had ruptured, the Daily Mail added.

However, following an operation he went on to make a full recovery and was otherwise fit and healthy.

Ms Brownlee, who has a six-year-old daughter with Mark, has now written a book about her experiences of being widowed at such a young age and talked about how she came to terms with her grief.

The 38-year-old, who lives near Sedgefield in County Durham, said: 'We were trying for a baby. We had lost a baby in November.

'Anyone who has tried for a baby knows there is small window every month during which it is the best possible time to conceive.

'We were at my mother’s house for my grandmother’s funeral. It wasn’t ideal as we were actually in my mother’s bed but we didn’t want to miss out on that window.

'We hadn’t been having sex for very long, we had only just started, when he collapsed.

'His last words to me were, "you’ve still got your socks on".

'I thought he’d collapsed because of a problem with his heart, but it didn’t cross my mind that he wouldn’t wake up.I called 999 and did CPR on him for half an hour before the ambulance arrived.'

Paramedics spent 40 minutes trying to revive him but he couldn’t be saved.