Hi Jon,
very interested to hear from you, since I see you live in Surrey as well! Where abouts are you? I live in Woking! If you ever felt like visiting sometime you'd be more than welcome.
The 925's wings denote it as a commercial model, the most deluxe and expensive cleaner money could buy - they were also used on the 900, which the 925 replaced. The 800 was just the standard domestic model, so it didn't get the extra styling touch of the wings.