The 6L19 is a general purpose double triode. The ratings given by Wireless World are slightly different to the data-sheet. Possibly the valve was improved over time.
The Mazda logo and the locating pip on the metal skirt.
The side view of the anodes showing the top of the control grid.
In detail the grid wire can be seen in notches in the support rods.
The thin glass tube envelope is 20 mm in diameter, and excluding the B8A base pins is 54 mm tall.