All caravans must have a gas regulator.
Older vans have a regulator which is fitted to the gas cylinder and a rubber hose from that tothe main van pipework inlet point.
It depended on what gas you were using as to which regulator was used, either one for Butane, or one for Propane.
Since 2004 all UK built caravans have had a fixed regulator mounted to the bulkhead in the gas locker and it is the same regulator for both Butane and Propane, just the connecting hose or "Pigtail" as it is known as is different for Butane and Propane.