Are the SBS/SAS the only true Commandos in britain?

The Royal Marines come under 3 Commando brigade, and receive the Green Beret, but are they still Commandos in the true sense? I have previously served in the Royal Navy and ped the Commando course, and worked alongside the Boot - necks, but I think the only true Commandos now are SF and perhaps 148 Cdo.. As the Marines carry out more of a light infantry role..