The Royal Marines should be in Company, not Squadron, formations.
40, 42 and 45 Royal Marines Commandos are each a roughly battalion sized formation organised in in Coy, not Squadron formations, although the Royal Marines do have some other units organised as Squadrons.
RN Frigates and Destroyers normally carry a section or so, depending on deployment, of Royal Marines, for minor landing/boarding ops. These days Royal Fleet Auxiliary ships (the supply and support ships of the Royal Navy) will also often carry a RM detachment if deployed in an operational area that justifies it.
The link below has a reasonable run down of their organisation.
http://www.eliteukforces.info/royal-marines/