This No7 bayonet was given to me by a British Soldier.  It has a swivel base and was used with the No4 Enfield & the STEN MKV.  The STEN MKV is the variant with the wooden buttstock,
 pistol grip and sometimes a front wooden hand grip. This variation of bayonet is probably the most collectible variant and therefore also the one of the most expensive to purchase ( at least for bayonets for the No4 Enfield)