But it is seen by many, nonetheless, as a symbol of English dominance. (And it doesn't represent all nations: Wales isn't included). I just happen to think that the Union Jack style branding (and the name) of GBR is a sop to the rabid English nationalists of the far right.
Exactly. The Union Jack is a symbol of the Union, which for many in Scotland and Wales is a symbol of the ongoing English suppression of Scots and Welsh language and culture. The Union Jack is as provocactive as the EU flag was to many in England prior to Brexit.
The naming of GBR is itself a symbol of gross insensitivity by the Westminster government, as a raspberry to Scots and Welsh intents to run their own services.
The Union flag flies alongside the Red Dragon at Cardiff Central, and the BR house flag flies next to the TfW flag. This hasn't yet reached the press...
The critical word there is
alongside.
If GBR had any sense or sensitivity, they would come up with versions of their branding that gave equal prominence to the Scots and Welsh flags. Many national retailers, such as Tesco, Aldi and Lidl manage to do that. I still have a Tesco bag with the Saltaire prominently printed on it. And even though Aldi and Lidl are German retailers, their promotional material isn't plastered with German flags, rather Union Jacks in England, and the Saltaire and the Dragon in Scotland and Wales.