Unknown Train Approaching Tunnel

Photograph of Unknown Train Approaching Tunnel
Loco number: Unknown
Loco name: n/a
Loco class: Unknown
Wheel arrangement: n/a
Location: Unknown
Subject type: Steam locomotive and passenger train
Date taken: 1940s
From/to: Unknown
Notes: Taken from first carriage window looking towards approaching tunnel entrance.
Region: Great Western Railway (GWR) ?
Power classification: Not rated
Designer: Unknown