A constituent of MP Mike Hancock has won a public apology over an "inappropriate and unprofessional friendship".
The "unreserved" apology was given by the Portsmouth MP at London's High Court to a single mother known as "Annie" who first visited him in October 2009 to seek his assistance as her MP and local councillor.
Solicitors for the woman announced in a statement that the apology was part of a "confidential settlement" in which the "vulnerable woman", who suffers from mental health problems, brought a claim for damages against him.
Mr Hancock, a former Liberal Democrat and now independent MP for Portsmouth South, said in a statement addressed to the woman: "In October 2009 you first came to me as a constituent to seek my assistance as your MP and councillor.
"Subsequently and over several months I came to your home on several occasions, sometimes unannounced and conducted a friendship that was inappropriate and unprofessional.
"I understand that you felt degraded. I did not treat you with sufficient respect.
"I made you feel deeply uncomfortable and discriminated against and I crossed the line.
"As a political representative there is a significant power differential with any constituent seeking help and particularly with you given your vulnerabiltiy of which I was aware.
"You had a right to trust me. Everyone should feel safe and should be able to have confidence in their political representatives and I am sorry that I made you feel otherwise.
"I have learnt from my mistakes and pledge not to act in the same way again."
The apology was described as "extensive and profound" by the woman's solicitors Birnberg Peirce and Partners, who also called for Parliament to now consider further regulation to cover relationships between MPs and constituents.
Master Leslie, a High Court official who approved the settlement in a ten-minute hearing, was told that Mr Hancock was currently an in-patient at the Priory Hospital in Southampton, and a psychiatric report had been obtained to confirm he had capacity to make his statement.
Her solicitors described "Annie" - not the woman's real name - as a single mother who suffers from mental health problems.
She brought her damages claim against the MP for his inappropriate behaviour four years ago, which had "caused damage to her mental health", said Birnberg Peirce.
A Liberal Democrat spokesman said a disciplinary investigation into Mr Hancock, which was put on hold pending the outcome of the civil case, would now be re-started.
His membership of the party has already been suspended.
The solicitors said Annie, who has a son, attempted to complain through the police, the Office of the Parliamentary Commissioner for Standards as well as the Liberal Democrat Party and Portsmouth City Council - "but has been blocked from achieving a remedy at each stage".
Her damages action was due to go to trial this week. But, following mediation two weeks ago, both sides settled the claim on confidential terms, which included the issuing of 68-year-old Mr Hancock's public apology.
A statement from Annie said: "I am pleased that there has finally been a resolution to what has been a long and hurtful ordeal for me.
"Since the incidents about which I complained happened back in 2010, my physical and mental health have suffered and I am grateful that I may now have some closure to this traumatic episode in the lives of both myself and my son."
Annie said she was pleased that Mr Hancock, from Fareham, Hants, now recognised that she did not bring her claim for financial gain but had only ever sought "justice and an apology".
She added: "Some Liberal Democrat councillors serving on Portsmouth City Council have sought publicly to discredit both myself and my motives for bringing an action against Mr Hancock, ignoring and even trying to undermine the independent investigation report commissioned by their own council from Nigel Pascoe QC."
She urged anyone else who had suffered "unwarranted approaches" from someone in public office abusing their trust "to come forward".
Birnberg Peirce solicitor Harriet Wistrich, who acted for Annie, described Mr Hancock's apology as "powerful and extensive" and importantly recognised "the in-built differential between an MP and his constituent that creates the potential for exploitation".
Ms Wistrich said: "Vulnerable adults, including those with mental health problems, suffer huge hurdles in persuading the criminal justice system of their credibility.
"I pay tribute to my client who has battled for justice for years and faced extraordinary hurdles.
"It is outrageous that she was blocked from having her complaint investigated and resolved by so many of the regulatory systems that should have been available to her.
"I hope that Members of Parliament will now consider this case and appreciate the need for the sort of regulation that already applies to most professions to be extended to these sort of relationships."