MA - GR (Gold Reference) and S (silver) - Made in England
Platinum, GX, GS, RX, RS, BR are all Made in China (except BX - assembled in Malaysia) , but designed and engineered in the UK.
MA's tweeters for platinum series are Made in Malaysia but the final assembly is done in MA's factory in China, with QC supervised and inspected by Monitor Audio's own staff.
Source: excerpt from Stereophile Magazine April 2010 / Interview with Dean Hartley - Head Designer - Monitor Audio