The Highfields that don't have bowls left are just because they've fallen off!
The 1st generation metal Highfields that ran two GLS lamps had a shallow but wide bowl. The Highfield I have is a 2nd generation one and is the very last one in existence which still had it's teardrop shape bowl still in place.
With lanterns of this type it can be confusing as to which is which, but in most cases these can be told apart by a fairly simple guide:
1 support arm: Revo Hatfield aka 'birmingham',
2 support arms: Liverpool Highfield (possibly made by either Phosco or Revo),
3 support arms, straight top with sealed bowl: Falks Beaufort,
3 support arms with curved top and open ended refractor-bowl: Hume Atkins,
4 support arms: Revo Precinct
Is the Beaufort the open refractor type without a bowl?No, small bowl.
That will be the Beaufort 3 then. I'd like to try save one of those if a location can be provided for it.