Are there any HETAS fitters in the room?
Would you reasonably expect CO to leak from a log burner during high winds. I'm not talking about a small leak, I'm talking about enough to fill a large cafe with vaulted ceiling and set of a CO detector
Not a HETAS fitter but if your CO detector is going off best stop using the log burner. Badly fitted log burners can cause potentially lethal carbon monoxide poisoning. You are exposing yourself to serious health risks by being exposed to CO. Carbon Monoxide strips the blood cells of oxygen, a silent killer. Part of my job is managing engineers working with gas appliances, CO fills up from the roof down, rule of thumb is if the CO alarm goes off, open doors and windows, turn off appliances and get out of the room, 1% CO in a room can be fatal. I can't express how serious this is. Were is your CO detector, it should be placed high up, this will give you more time to get out.