Kind of remeinds me of a Jack Heyworth. I've seen quite a few of these around in musty old saxophone cases and techs' mouthpiece drawers.
But
I always thought that although they had that Lawton like groove, they just had normal 2 screw ligs.
I think they alos went under other names, Continental and were maybe also made be Lelandais???
I haven't seen that lawton style slider lig apart from on morfe modern mouthpieces, and a Macaferri who I think patented a version of it.