Elderly residents across Kent and South London are urged to be vigilant as police step up Operation Minstead, one of the biggest rape investigations in British history.

A public briefing is being held today in Crofton Road, Orpington, to reassure residents more than 50 Serious Crime Unit officers will be carrying out house-to-house inquiries within a half-mile radius.

It is the latest development in Operation Minstead, the hunt for a "gerontophile" rapist who preys on single elderly women and is responsible for 26 attacks three of them rapes over 11 years.

The rapist operates in cluster areas such as Orpington, Brockley, Forest Hill, Sidcup, Beckenham and Catford and police believe he may have links there.

Detective Chief Inspector Simon Morgan, who is leading the investigation, said: "He either lives, works or has some connection with someone he visits in Orpington.

"This could be a child, a school or a job. We want people to come forward and tell us if they know of anyone who matches the description.

"Three of his victims have gone to their grave not knowing who their attacker is and we are determined to catch him. We believe he is sorry for what he does and he can get help for his condition."

Police are raising awareness in Orpington following an attack on an elderly lady in Shirley, Croydon, on October 13 last year.

It came three years and three months after the previous one and threw up a vital clue: a print of a size 10 Nike Air Terra Contego sole.

This was significant because the rapist had always been careful not to leave any evidence. For instance, police have never found any fingerprints where he has struck.

Portrait of a rapist

5ft 9in tall, light-skinned black man, of slim to medium athletic build, has a soft-spoken south east London accent and wears a dark all-in-one catsuit, balaclava and gloves.

Enters through the rear of a house by removing an entire window intact.

Often goes for homes with a side entrance and uses tools found in a garden shed to break into the property.

Cuts telephone lines, turns off electricity at the meter and removes light bulbs.

Once with the victim, he speaks in a soft voice and shines a torch in her eyes.

Believed to enjoy the company of elderly women and often spends hours in victims' homes.

Known to show remorse and retreat when challenged.

Over the next few weeks, every police officer in south east London will be shown a video of how the pervert operates and will be urged to report all burglaries and attacks bearing his hallmarks to the investigating team.

The team has spent the past few years scouring records, including DNA databases, from all over the world and has eliminated more than 16,500 people from its inquiries.

There is also a £10,000 reward for information leading to the attacker's arrest and conviction.

Was attacker once a victim?

Sex attacks on elderly women indicate a "very dented self-image" and someone who has suffered severe abuse.

Cedric Hart, a criminal psychologist, says the man is more than likely to have been abused by his father or an older brother.

Mr Hart, who works for the prison service in Shropshire, said: "He will have had a disturbed early childhood and adolescence.

"He will be unforgiving of his father, or whoever inflicted the abuse, which would be sexual or severe psychological torment. It may well have been hidden from his mother until she was forced to face up to it.

"He will feel ambivalent towards his mother and possibly feel she should have done something about it.

Mr Hart added: "I do not think this guy's sole intention is to get a sexual buzz. It's more about inflicting terror and psychological abuse by using sex as a weapon."

Anyone with information can call the incident room on 020 8649 1556.

Elderly residents in Orpington can seek crime prevention advice by calling Bromley police on 020 8284 8113.