Well that was a mistake. Having extracted the switchboard from the shed and written it up, I previewed the post and then closed the browser!
The British Switchboard, Charging, No.5 is a simple beast. All switches are identical, two pole, two way, with two off positions. The connections on the rear of the switches are different to those on the Canadian switchboard and the screws have brass plate cable clamps to take the conductors directly. Connections are marked (clockwise from the 10 o'clock position) L (red), 1 (red) 2 (black), N (black) 2 (red) 1 (black).
Upper switches select "Charge Battery" in the 3 o'clock position (all others are "Off") Left hand switch is Battery 1, Right hand switch is Battery 2.
Lower left hand switch selects charging source; 9 o'clock is "Vehicle Dynamo", 3 o'clock is "Power Unit".
Lower right hand switch selects "Set Supply From" to "12V Output" terminals, 9 o'clock is Battery 1, 3 o'clock is Battery 2.
The "Internal Lighting" terminals are common to the "12V Output" terminals.
Robert's "Switchboard C5" is rather more complicated, and the extra battery terminals are clearly a later (bodged) addition, as one of the switches has had to be rotated slightly (presumably to clear the nuts/washers on the added terminal) and re-fixed using some modified washers as a mounting adapter! (I don't really see what the point of it was, other than to make Battery 1 and Battery 2 accessible from either side of the switchboard.
It's then "flipped" in that the upper switches select the "12V Output" source (left switch Battery 1 or Battery 2) and "Internal Lighting" (right switch Battery 1 or Battery 2), while the lower switches allow each battery to be connected to either of the charging sets.
The other strange part is that the 'inner' (added) battery terminals appear to be marked "Charge". I suppose a detailed look at the panel wiring is next.
Chris.