I'm always amazed at what I read on the internet that passes as facts from people who are not in the business, but feel they talked to someone (say a distributor) and think it's correct. Here's the truth, as told to me by current Celestion reps (I know four of them), one former Celestion lead speaker engineer (Duncan Boniface), and multiple wholesale parts suppliers in the US who sell Kurt Mueller & Celestion parts.
1) Kurt Mueller still supplies SOME cones to Celestion, but by no means all. There are other companies in Malaysia, UVM and others for example, that supply Celestion cones.
2) There are cones/spiders/voice coils made in Malaysia & China, as well as a small percentage the UK, but the majority are made in China. How do I know? One of my US suppliers gets their cones from China instead of the UK. They've offered them to me. I declined. I get mine from Kurt Mueller in the UK directly.
3) The paper pulp type, content and mix are NOT the same as the 50/60's. The wood fibers the cones are made from now are no longer the LONG fibers due to the fact that it's no longer old growth wood being used for the paper pulp for the cones. Why do old guitars from the 50's sound better? Old growth wood, not newer trees.
4) Many of the cone/frame machines were shipped from the UK to China and set up there in 2003. Duncan Boniface oversaw the transition. There is a small # of people actually building guitar speakers in the UK for Celestion. Most of it is pro audio, not guitar speakers.
5) There was most definitely a higher rate of failure, with inconsistent speaker builds and such from 2003 until it stabilized about 5 years ago (2009) from China as compared to the UK built models of the same type. Why? Training, parts issues, suppliers, materials, glue changes, etc. There's this disclaimer often used... "Specifications Subject to Change Without Notice"...maybe some of you have noticed it before.
With all due respect to some of the posters in this thread, more research before you type would be advised.