The victory on Tuesday was Richards' first since Captain Shillalae won at Dunkeld in November 1996.
Jockey Christine Puls had the ride on Niamh Chinn Oir on Tuesday and was also aboard Captain Shillalae in Richards' previous success.
Richards, 73, explained he gave training away in 1998 after commencing a new job then took his licence out again in 2016 following his retirement from the workforce.
"I gave it away because I couldn't give the horses the time," Richards told racing.com.
"Then I thought I'd better take it out again because I've retired.
"It gets me out of bed at five in the morning."
Richards said he got his passion for horses having spent eight years in the mounted division of Victoria Police.
Niamh Chinn Oir was purchased for $8800 and was having her fourth start for Richards.
"I didn't know how she would handle this but I brought her here because she won on the synthetic at Pakenham," he said.
"I think the bottle of Glenfiddich, 12 years old, will be out tonight, or maybe the Chivas Regal that the other part-owner bought me for Christmas."