A man who was allegedly filming up a woman's skirt on an escalator at Martin Place station was detained in a citizen's arrest on Friday morning.
Michael Fitzpatrick, a lawyer who was on his way to work, said he was also on the escalator, which led up to the exit of the station, about 7.45am.
"I was just walking up the escalator and, towards the top of the escalator, a man who was in front of me yelled out to another man on the escalator beside us - who was also going up - words to the effect of, 'I saw what you did' or 'Stop filming up that girl's skirt,' " Mr Fitzpatrick said.
"The man, I later found out, apparently had his arm outstretched with his camera phone and he was filming up the girl's skirt in front of him as he walked up the escalator."
Mr Fitzpatrick said that once the man who yelled got off the escalator, he approached the man who was allegedly filming.
"The guy kind of just kept a hold on his arm and held onto him and said 'No you're not going anywhere.' "
He and another man then approached the pair to see that the alleged offender did not leave.
They were soon joined by station staff who had called the police.
The police arrived about 30 minutes later, said Mr Fitzpatrick who had to leave quickly afterwards to get to work.
Of the citizen's arrest, he said that he was "very glad - sad to think that people are doing these kind of things - but glad that someone saw it, and glad that someone said something and did something about it".
NSW Police said that a 51-year-old man was arrested at Martin Place and taken to Day Street police station where he was charged with two counts of filming a person's private parts.
He is due to appear at the Downing Centre in February next year.
