Luggage on Virgin flights

Hi guys,
Does anyone know what the deal is with car booster seats on Virgin flights? I know they are carried free of charge, but do they go on as hold or hand luggage? Is it better letting the agent tag them, or wrapping them in a black bag with our details on it etc?
Thanks in advance!
Gaz.
Does anyone know what the deal is with car booster seats on Virgin flights? I know they are carried free of charge, but do they go on as hold or hand luggage? Is it better letting the agent tag them, or wrapping them in a black bag with our details on it etc?
Thanks in advance!
Gaz.