The surface is the old style the GWR was fond of, a grey slate tile with a diamond pattern pressed into it. I presume that's long gone. The photographer is indeed standing close to the Up Main side of the central island platform.
I always thought that Falcon won the prototype loco competition between builders a bit unfairly. Brush devised a twin engine (not favoured) high speed engine (not favoured) loco, with electric transmission but with two small generators, which I don't think anyone else ever did. It's competitor Lion by BRCW had one large Sulzer (favoured) medium speed (favoured) engine, with one large generator. The competition result was that Brush were announced the winners, and got the huge order for the Class 47, but it was to be built to the now proven Lion design. BRCW went bankrupt.
Falcon didn't "win" anything.
What happened is BRCW realised that by the 1960's the market was shrinking, they weren't big enough to compete so decided to get out of the rail business. They renamed themselves and became a financial investment business, finally getting wound up in the 1990's. BRCW lost interest in Lion very early on and gave up on support
The class 47 order went to Brush by accident.
What happened is that Crewe works couldn't cope with the planned delivery schedule for the class 45 Peaks, so part of the order was transferred to Derby. It was then realised that Crompton-Parkinson couldn't hit the delivery schedule for one production line, let alone two so the later Derby builds used Brush electricals instead and became the class 46. Even then, production was too slow, BRCW had closed so Brush was asked to open a third production line for the last 20 class 46 (they had spare capacity as the class 30 build had finished). Brush naturally said "yes please"........but then someone at Brush had the idea of using the diesel and electricals already ordered but in a new stressed skin body based on Falcon (which itself took styling cues from the same study as resulted in the Hymek)
By the time Brush were asked to set up the third production line, they and EE were the only significant external companies still in business capable of building a large loco, and there was no way EE was going to build a Sulzer engined design, so BR had no choice but go to Brush for help.
As to why the class 47 became the "volume" type 4, BR were licenced to build it in-house and so kept the unions and workforce happy, while EE would have been unlikely to allow a DP2 derivative to be built outside its own workshops.
While on the topic, Kestrel used Maybachs because at the time both Bristol-Siddley and Brush were part of the Hawker-Siddley empire.
BR used so many Sulzers because Vickers at Barrow had been pushed by the government into creating a submarine engine production line in anticipation of need during the Korean war - a need that never happened. So the government pushed BR toward Vickers in an attempt to provide alternative work
