Robert Seabrook QC, for the Customs and Excise, was asking her why there was a year's delay in bringing the lawsuit.
Lady Foster is now married to the architect Sir Norman Foster but at the time of the incident in November 1990 she was Mrs Sabiha Knight, married to the News International chairman, Andrew Knight. She said: 'It was very difficult because my husband and I were separating . . . It was a very painful time.'
Mr Seabrook then said: 'You are suggesting this was so painful that you did nothing about the claim you are making for a year. When did you decide to get married?'
Lady Foster did not reply and left the witness box in tears.
Lady Foster, of Battersea, south London, and her daughter are suing for damages for false imprisonment after being arrested for allegedly obstructing a search of their baggage, and 'slander by conduct' - being marched publicly through the airport.
They claim officers treated them with hostility, rudeness and sarcasm during a check for documents relating to the breaking of UN sanctions against Iraq. The Customs say the women brought the arrest on themselves by being aggressive.
Mr Seabrook referred to white homeopathic powders in white paper wrappers, in Lady Foster's luggage. 'As a very experienced international traveller and well-informed person, you would know these could be of considerable interest to Customs officers because very often drugs such as cocaine are wrapped in such a way.'
Lady Foster: 'Yes'.
She was later asked why she had originally said eight or 10 Customs men surrounded her, when there were only four. Lady Foster said there were at least six or seven. Mr Seabrook: 'You have increased the number to try and create an air of harassment which simply did not exist . . . That's the truth, isn't it?'
Lady Foster: 'It is not the truth.'
The court has heard that Lady Foster and her daughter, India Langmead, were released after she revealed she was married to the chairman of News International.
Mrs Langmead, 27, said the Customs officer who dealt with them, Timothy Entwhistle, was 'sarcastic, argumentative and hostile and looked us up and down as though we were something he had trodden in'.
The hearing continues today.Reuse content