When looking for a partner, the majority of women cite good sense of humour as an essential requirement. And in the shark infested world of online dating, we assume their only experience of porridge to be the kind found on the breakfast table. Not so for the increasing number of ladies who write to strangers in prison.

Prior to the internet, prison pen pals relied on snail mail. However in recent years, the advent of websites such as MeetaPrisoner.com, InmatesforYou.com, and even GayPrisoners.net have made it easier for people to connect with potential suitors on the inside. Whilst prevalent in the States, each facility differs as to what they allow or disallow, but the general rule is that anything being sent to or from an inmate goes through a screening process. In the UK, people who wish to write letters to inmates can do so via www.prisonerspenfriends.org.

Prisoners in the UK have no direct access to social media or the internet in general, and letters are still the preferred means of communication. Alex Cavendish, Social Anthropologist and former prison inmate, says; “In theory, a percentage of all outgoing letters are randomly checked by the censor's department in each prison (usually 10%). However, if the inmate has been convicted of domestic violence, a sexual offence or stalking/harassment, then all letters are supposed to be read.”

Most of us struggle to identify with the type of woman who would actively search for a partner in prison. We read the sensational stories in the Press which tend to veer between pity and disdain. Are they lonely creatures in search of emotional dependence from a captive audience? Or manipulative sociopaths living vicariously through ‘celebrity’ prisoners?

Fatema Saira Rehman, the woman who wrote to and later married notorious lifer Charles Bronson, once said of her correspondence; “I never expected anything. I thought to myself, he's probably got so many women writing to him, he'll throw it away because it doesn't mean a thing. And I'll go on being a lost soul."

Murderer Charles Manson in 1970 (Getty Images) (Getty)

On the other side of the pond, psychopathic mass murderer Charles Manson recently called off the wedding to his pen pal, Afton-Elaine Burton after discovering that she was secretly ordering a glass coffin for her intended, with a view to charging spectators after his death.

Cavendish believes it to be a highly complex issue and agrees that major factors to consider are dependency and control; “Dependence works both ways - financial for many prisoners, particularly those who don't have family ties, as well as emotional.”

With regards to the type of women who write to prisoners; “I'll be honest and say that a fair few of the female correspondents are lonely women who often have body-image concerns (many of those whose photos I've seen tend to be overweight.) They feel perhaps that a prisoner is likely to be less judgmental and more appreciative of any support - emotional and/or financial.”

Many women (and men) choose to reach out simply to provide friendship and compassion to those behind bars. Their actions provide a much welcome lifeline, a window to the outside world. (Getty) (Getty Images)

For these women, connecting with a man who is locked up for the majority of the day with little else to occupy his time, you’d be forgiven for assuming that the inmate has no choice but to remain faithful. However as Cavendish observes, prisoners can benefit fiscally from these courtships; “I’ve known male inmates who have several pen pals, and they live a very comfortable life inside on the regular postal orders or cheques that get sent in. I’ve met straight young prisoners who are keen to find male ‘sugar daddies’ willing to fund their tobacco or drug habits whilst inside.”

Yet it would be wrong to claim that all inmates exploit the situation and all pen pals on the outside are lonely and looking for love.

Many women (and men) choose to reach out simply to provide friendship and compassion to those behind bars. Their actions provide a much welcome lifeline, a window to the outside world.

In the UK prisoners can also be placed on a home detention curfew, be expected to permanently reside at a pre-approved address and need to obtain prior permission for a stay of one or more nights at a different address. (PA)

Yet even in platonic cases the lines can get blurred. Georgina Rigby was 28 and working in the field of drug misuse when an inmate contacted her. “He wasn’t a direct client, but I recalled him living on the same estate where I grew up. It was platonic at the beginning. I think at first he genuinely wanted someone to talk to, and as the letters progressed they did become more sexual...I could tell that having a sympathetic woman to write to made him feel good, and no doubt gave him some fantasy material. As for me, I guess I felt wanted and liked.

"Thinking about it now, several years later, the letters allowed me to be intimate at a distance. To be my ‘best self’ without the physical and personal flaws that he'd encounter face to face.”

For those who instigate and sustain a relationship with a man imprisoned for a lengthy period of time, physical contact is obviously limited. They often never progress beyond the courting stage. As observed by Clinical Psychologist Dr Stuart Fischoff; “The love object is almost irrelevant at this point. He's a dream lover, a phantom limb."

Hybristophilia is described as a condition whereby women are sexually aroused by and responsive to the men who commit heinous crimes. (Getty)

However there are those who do succeed in establishing a ‘real life’ relationship with the stranger they’ve connected with. It does occur - but as Cavendish points out, these instances are rare; “There are just too many variables, including licence conditions that severely restrict most offenders from starting new relationships or moving their place of residence until their licence has expired. In most cases this period can be half of the original sentence - or for life in the case of life sentenced prisoners.”

In the UK prisoners can also be placed on a home detention curfew, be expected to permanently reside at a pre-approved address and need to obtain prior permission for a stay of one or more nights at a different address. All of which would put a significant strain on starting a relationship or continuing with one that began from behind bars.

In short, the fantasy of these type situations rarely match the reality. Similarly there are women who are fascinated with writing to an ‘A’ list prisoner, those who make misguided attempt to understand the man behind the monster. Their motivation is born from compassion, low self-esteem or ill-advised intentions. However there are others who are attracted to men who commit extreme acts of violence, such as rape or murder.

The notorious Soham killer Ian Huntley still attracts attention and interest from women on the outside (PA)

Hybristophilia is described as a condition whereby women are sexually aroused by and responsive to the men who commit heinous crimes. Often referred to as the ‘Bonnie & Clyde Syndrome.’

In this instance the Passive Hybristophile will often contact someone in prison - someone that they only know by reputation in the media. As in the case of Ian Huntley, the notorious Soham killer. He still attracts intense media attention and interest from women on the outside. In reference to Huntley, one such woman, Joanne Rutledge, is quoted as saying; “He’s had thousands of letters since he got convicted but I’m the first stranger he’s contacted.”

More recently during the Oscar Pistorius trial, hordes of women could be witnessed calling out support to him on a daily basis – something I observed personally when watching the news reports.

And perhaps most baffling is the case of Lostprophets singer Ian Watkins. Despite the fact he pleaded guilty to a number of sexual assault charges against children, several women have since written to him in jail. One such fan, devastated at the guilty verdict, reportedly said; “He brought so much meaning to the lives of his fans that without the Lostprophets we’re empty. I am in touch with female fans who have written to him sending pictures, telling him they’d wait for him when he is released.”

Since he was jailed, deluded supporters set up and regularly contribute to Facebook groups. And although they are frequently taken down, the fans remain active in voicing their support;