Doormen across Berkshire were spot checked by Thames Valley Police and the Security Industry Authority (SIA) on Saturday night to ensure they met licensing conditions.
Warnings were given to two men in Slough, another two in Maidenhead and seven in Windsor for non-compliance with SIA licensing conditions for reasons including failing to disclose criminal convictions, and not displaying a valid SIA licence.
Thames Valley Police licensing co-ordinator Ben Clarke said: "Well-trained, licensed door staffs are key to making the night-time environment safe in our towns and cities.
"At best, they are able to anticipate potential offences and prevent them getting out of hand or at least keeping the public safe until the police can arrive.
"Untrained, unlicensed door staff could have the opposite effect and make the situation worse.
"Having this type of scrutiny has obvious benefits for the public, the police and the premises themselves, making sure that everyone is compliant to the SIA standards."
SIA head of investigation Darren Woodhouse said: "The investment of time and personnel by TVP and the SIA gives a clear message to the public that we are committed to ensuring their safety.
"We are pleased with the result of this operation as it demonstrates to those involved in the night-time economy that we insist upon full compliance with SIA licensing and its conditions."
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