A 22-year-old man who allegedly flashed his backside at the Queen during her visit to Brisbane will not be prosecuted for wilful exposure.

Sydney man Liam Lloyd Warriner is accused of dropping his pants as the royal motorcade drove past in October.

Police today told the Brisbane Magistrates Court they are dropping the wilful exposure charge against him.

They will proceed with a charge of public nuisance.

Defence lawyers say the 22-year-old will plead guilty when the case is heard next month.

Tens of thousands of people turned out in Brisbane to catch a glimpse of the Queen in her first visit to the city in almost a decade.