Hello Davey,
You say you have purchased a new caravan, if so you have probably been supplied with the new standard regulator set to 30mB. This is the new common standard pressure for both butane & propane in the UK and most of Europe.
Previously, we used 28mB for butane and 37mB for propane, which effectively compensated for the slightly lower calorific value of propane by using the higher pressure, it also meant that a propane flame may have sounded more forceful.
I'm not sure that this new standard is good thing, its basically the UK using a less effective method in the interests of European Harmonisation.