Five months later, he asked her to a meeting at the premises of his firm, Tony Dart Solicitors and Advocates, to discuss her outstanding bill.
In a statement to the tribunal Mr Dart said: "She was quite animated and said she had been in contact with someone via the internet which could lead to her being paid lots of money for participating in a porn movie.
"She shooed me out of my chair in order to use my computer and went onto a website which contained adult porn. She showed me a couple of clips over a few minutes.
"Before leaving she did again suggest that I might care to take some photographs of her, but she would not feel comfortable doing so at my offices."
After the meeting the pair communicated further, and Miss BC recorded a phone conversation.
Jonathan Goodwin, representing the Solicitors Regulation Authority, told the hearing Mr Dart made his intentions clear.
Mr Goodwin said: "He was discussing with a vulnerable female client the settling of his bill 'rather than in cash but in kind' and these were his words.
"[Mr Dart] made several attempts to contact Miss BC to make arrangements.
"From the recordings it was clearly intended that there would be explicit photographs and there were clear implications regarding sexual activity."
The tribunal heard that Mr Dart asked Miss BC not to send explicit texts because they might be discovered by the authorities.
He said what she suggested "would be wonderful and would be nice" and "I mean I don't expect that a session is going to clear the bill".
He went on to say: "I'm sure we could think of some bright ideas where I might end up owing you some money, but at least that would clear the debt as far as I'm concerned."
After hearing evidence in mitigation, the tribunal "accepted that this misconduct occurred in a long unblemished career but it was not a one-off but a series of contacts."
In evidence submitted to the hearing, Mr Dart said: "I offer my profession and the tribunal my abject apologies for my failure to comply with the standards I know I should have observed."
Mr Tinkler, the chairman of the Solicitors Disciplinary Tribunal, who oversaw the hearing said: "There was no suggestion that the respondent [Mr Dart] had committed a criminal offence, but his conduct so greatly and clearly undermined the trust the public would place in solicitors that in the view of the tribunal he could not continue as a member of the profession."
Mr Dart was struck off the roll of solicitors and ordered to pay costs of £12,000.
Speaking after the case, he said: "I don't want to make any comment. This has been a very difficult time for me. I have got to live my life and it is really tough. It is the end of my career. It is a pretty awful time for me and my family."