A woman who stripped off and attempted to steal lingerie from Harvey Nichols is understood to have been banned from the store.
The suspected thief is said to have taken off her clothes and put on a stolen bra and knickers set, while stood in front of a second floor window yesterday.
She then placed her clothes on over the top in an attempt to steal the lingerie.
But city centre police officers said the woman was being watched by hundreds of onlookers on the street below, which was packed out with Manchester Day spectators at the time.
Two police officers overheard the cheering crowd and looked up to see the crime in progress.
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The officers alerted the store and the woman was detained.
It is understood the woman has now been banned from entering the department store.
The original post on the Greater Manchester Police city centre Facebook page said: "In a bizarre end to Manchester Day a short time ago a woman has allegedly stripped in Harvey Nichols, put lingerie on then put her clothes over the top in an attempt to steal said lingerie.
"I can only assume she did not know she was doing this in front of a 2nd floor window.
"2 of our officers attention was been drawn by hundreds of people cheering so they've looked up & seen this crime in progress, alerted the store & detained the woman."
Harvey Nichols has been contacted for a comment.
