(06 Jan 2017, 3:47 pm)South Tyne Lad wrote Any non-DDA bus can be used on a commercial fare paying service for up to 20 days of a year without being classed as illegal, A exercise which GCT will no doubt be using.
What you're referring to would be a very loose interpretation of the legislation, and one which I personally doubt would stand up legally if challenged. However, it would not apply in the case of W177SCU regardless, as the bus is not 20+ years old.