[peel] Vintage Peel - Reel tape format?

[rockerq@...]

Tonight I finally got around to listening to one of the reel-to-reel tapes 
from The Decktician.

Quality is pretty good, despite the fact that it runs at 3.75ips. The tape 
consists of tracks recorded from John Peel shows, around 1974 - On this 
particular tape John's links have been edited out, although the occasional cut 
off syllable is enough to confirm that they are indeed from Peel shows.

The deck I am playing back the tape on is a standard consumer "quarter 
track" quarter inch tape deck - tracks one and three are stereo in one 
direction, and tracks four and two are stereo on side two, running in the opposite 
direction.

On this tape, when I select stereo playback (tracks one and three) I get 
one track in the left speaker playing forwards, plus another track in the 
right speaker playing backwards. When I reverse the tape I get the backwards 
track playing forwards in the left speaker, plus the original forwards track 
playing backwards in the right speaker.

I have two theories which would acount for this:

The tape is recorded in mono half track - with a mono recording taking up 
half the tape in each direction.

or... The tape is recorded in stereo quarter track, but the left and right 
channels of side one are recorded to tracks one and two, and the left and 
right channels of side two are recorded in the opposite direction, to tracks 
three and four.

Neither of these are formats I have come across before - anyone else know 
if either format was ever used in commercially available machines?

Since the audio source in those days would probably have been mono medium 
wave radio, I suspect that this conjecture is irrelevant, and that either way 
we end up with a fairly decent mono recording.

Cheers!

Rocker