What British trainer has produced the most World Champions?

TBooze is correct, as far as numbers go Charles Atkinson has produced by far the most World Champions. 10 in total, 7 WBC AND 3 WBU. None of his fighters ever lost to a Mexican and none of his fighters had more than 10 fights when he took them on, seriously impressive.
John Conteh came out of his fathers gym ( Charles Snr) in Liverpool before heading off to London, but Charlie JNR also promoted in Liverpool and made the Conteh vs Hutchins fight which saw Conteh win the WBC light heavyweight title.
He took a 20/1 underdog and knocked out Humberto Gonzalez at the LA Forum in 95. What a fight that was.

 

Grant Smith with Sunny and Charlie Edwards.

Also think his son Dalton Smith will go all the way.