Ant hits the nail on the head, and it isn't just the UK that suffers from this unpleasant side-effect of "globalization."
As for the fact that "British bikes" use the same components as all others so there isn't a true Brit bike; that's a bit disingenuous.
When I was drooling over the bright red Hetchins leaned against the bike shed at my high school in Wednesfield, in 1964, it sported a Campagnolo gruppo. (And, incedentally, I still buy Campagnolo -- so this supports the theory that excellence is a powerful branding tool).
My Canadian-built Marinoni was built by a French-Canadian welder at a company established by an ex-pat Italian. It has the aforementioned Italian components.
But this does add an interesting "component" to the discussion. Why shouldn't/couldn't the UK produce some good bicycle components that at least occupy a solid place in the niche market? Has it been so long since British manufacturing collapsed that there are no good machinists around?
I own several of the US brands of hubs, including Phil Wood and White Industries. These are absolutely beautiful! I also have Chris King headsets on 2 of my bikes. I own a pair of Phil hubs that I used for 20+ years. The new ones incl. cassette R hub that can be disassembled w/ 2 5mm allen wrenches.
The UK meanwhile hasn't to my knowledge built a derailleur since
Benelux (originally a French-English collaboration) and
Sturmy-Archer is in Taiwan.
Brooks, cast adrift when parent Sturmey-Archer collapsed, was gobbled up by Selle Royal.
Why is this? At the risk of being provocative, did the highly centralized/unionized (no, I'm not anti-union) factory culture of the UK discourage innovation and individual enterprise?
I'm imagining here one of those little derelict factory buildings springing to life as a high bling-factor producer of bicycle components. Put those on yer bike and ride it.
Lastly (for now) the problem in all constituencies is the cost of producing a bike for Everyman in today's market. "Stuck in the 50s" isn't an issue when it comes to this sort of machine. I have been pondering the question: How does one produce a practical bike today -- for, say, around £250-500?
Raleigh was indeed the British flagship. Too bad it sank.