Seems like Deacy never made the official announcement, but it had to be somewhere in between the release of 'No One But You' in late 1997, and the recording of 'We Will Rock You' with 5ive in 1999.
As far as I'm concerned, John Deacon also took part on the recording sessions to complete 'Made In Heaven' in 1994/1995.
He also performed along with Brian, Roger, and Elton for a performance of 'The Show Must Go On' at the Bejart Ballet in Paris. That was in 1997 if I remember well.
He had to pay his own tribute to Freddie that's why he was involved in these projects.
He wrote letters for OIQFC after 1997 even, so what? No... John accepted that Queen is not being anymore since Freddie's death.