General Service ⁽⁷⁾

N.P.C.S. ⁽¹⁴⁾

Unusual Coaches ⁽⁴⁾

Diner Coaches ⁽⁸⁾

Composite Coaches ⁽⁴⁾

American Specials ⁽⁷⁾

W.C.J.S. ⁽⁶⁾

Royal Trains ⁽¹⁰⁾

Railmotor ⁽³⁾

Motor Train ⁽⁵⁾

Wolverton Works ⁽⁴⁾

N.P.C.S.

Interior of a TPO

Click on picture for bigger image.   Photo Ref Lnwrs/75

This appears to be a cove-roofed vehicle and so may well be one of the batch of four to diagram 392 – an internal shot to complement the previous official external photograph. The details above are based on this assumption.