Suspect news, frankly
Every time I have been in China, there was simply no practical English language short wave signal anywhere be it city or province. So I no longer carry a SW radio on travels as there is no UK originated content audible on it.
I doubt anyone owns a SW receiver in China these days either.
All in all I find it unbelievable that China jams these non-existent (English language??) broadcasts to a non-existent audience.
And to seal the demise of AM long distance broadcasting, the BBC itself closed down its flagship MW transmitter to Europe that used to allow all Eurocrats to listen in their standard car radios all day any day.
If the UK wants to get a good PR message out to Chinese citizens, how about ceasing with the humiliating hoops they have to jump through to get a simple visitors' visa to the UK?