I think the branding during the franchise years has been one of it’s more beneficial elements. The only successful BR brand was Intercity, which I think is because it had a defined service (long-distance trains), defined images (The font, the HST, the swallow livery) and defined service levels (1st class, buffet cars).
London Underground has been a success for decades, for similar reasons. The TfL brand is not what has made the branding in London a success, but rather it was the roundel, the map and the physical infrastructure that has defined the brand. It became an image of London and it’s success has been exported to other modes.
The franchise brands has enabled the definition, identity and service levels of each of the TOCs, with their brand succeeding or failing as a result of their own performance. Not many brands have succeeded, but some have. Virgin had succeeded, helped by the fact that it was a successful brand to begin with. Northern has not been a successful brand, while TPE has only recently become a strong brand.
There are other successes too: Tyne & Wear Metro, Manchester Metrolink are successful and are images of their city. Others have failed: Southern, SWT, South Eastern and before them Regional Railways and Network South East.
Going forward I hope branding takes a leaf out of the books of Intercity, Virgin, Transpennine Express, Tyne & Wear Metro and Manchester Metrolink, because the brands can help the service too.