During a lengthy career, Dennis covered 136 Test Matches and more than 250 One Day Internationals since his first match in 1976.
He has also been the PA announcer for Middlesex County Cricket Club during this time.
We're hoping to find someone with presence and personality
The new PA announcer will cover a variety of county and club matches at Lord’s in 2014 including Test Matches and a One Day International against Sri Lanka, and the much-anticipated MCC v Rest of the World Lord’s Bicentenary celebration match featuring Sachin Tendulkar and Shane Warne.
MCC President Mike Gatting, said: "The impact the PA announcer has at Lord’s is huge – as Johnny proved during his great career here. Their voice can inspire spectators and players alike, and adds to the unique experience that is a Lord’s matchday.
"MCC is looking for someone who can help to build the special atmosphere that exists during matches at Lord’s. Anyone who works at MCC will tell you what a unique place this is, and the Club is hoping to find someone with the presence and personality to fit in with that."