I read on another forum that only the Celestion Blue Alnico is made in England.
Dave at Avatar Speakers, www.avatarspeakers.com told me that the Vintage and Heritage 30's that he sells come from China. He said that he has not had 1 customer complain about the difference in tone.
It would be very interesting to know where each model comes from.
I don't think that Celestion would allow the process to be any different, gluing time, etc. Why would they. It would not cost them anymore to simply show the Chinese manufacturer how to do things to their specs. They might have already known how simply from cloning them for years.
I don't think they had to open a factory either. They probably looked around and found a factory that was already making decent speakers, had the right equipment, and could be trained on how to make Celestions.
A really good example of this is Plasma TV's. I design and build Home Theaters, Home Audio Systems and Lighting Control/Home Automation Systems. Most plasmas are made by the same few manufacturers in China and South Korea to each companies specs. They all look a little different, but lots of them are the same inside. Others shine above the rest because the manufacturer is making them to the name brand's specifications.
I don't like outsourcing, but it has become the way of life for most companies. Countries like China, Indonesia, India, and South Korea don't have the EPA breathing down their necks. It is probably far cheaper to buy off a foreign government than to pay the EPA off (although I have seen it done).
Honestly, if Marshall had their stuff made in China, it might be better quality.