He dropped in on filming for a Christmas special in Cardiff in a break from appearing at a theatre nearby.
Baker said he was impressed by current Doctor David Tennant - and Kylie Minogue who also will appear in the episode.
"The atmosphere was as special as I remembered it," he explained. "I had a moment of envy seeing David surrounded by bizarre aliens.
"We chatted. And I met Kylie Minogue, who was relishing the opportunity to demonstrate her acting prowess on TV again."
He added: "It looks like it will be a superb Christmas special."