The ECC807 from Brimar is an audio double triode and replaces the 13D7.
Brimar describe the ECC807 as being specifically designed for use in high gain pre-amplifier stages operating with low level input voltages. The Mullard ECC83 was designed for the same application and has very similar operating characteristics but has a higher overall gain.
The getter ring is isolated from the top mica by a support plate thus ensuring that the getter is confined to the top of the envelope.
This image is looking onto the ends of both triodes, the grids can be seen through the holes, the grey plate below the letter E on the glass is the intersection electrostatic screen.
This image shows the construction of the anode box.
Thanks to Alex Dutton for sending the images and data-sheet.
The thin glass tube envelope is 22 mm in diameter, and excluding the B9A base pins is 49 mm tall.
Reference: Datasheet. Type ECC807 was first introduced in 1964.