Present at the ceremony was a relative of Mr Ellis, Linda Ellis of Bridlington, Scarborough mayor Hazel Lynskey and Wayne Murray, the Scarborough museum owner who spearheaded the campaign for the plaque.
Mr Ellis was the first victim of the Scarborough Bombardment on December 16 1914. He died at 8am that day outside his place of work , Clare and Hunt chemist in South Street, South Cliff, Scarborough.
The green and gold plate will be put in place on the building – now Three Works Gallery – on Monday December 16 at 8am.
“I think it is important that as many people as possible know who Leonard was and what happened to him,” said Mr Murray, who runs Scardeburg to Scarborough, a social history museum in the Market Hall and Vaults in St Helen’s Square.
“I don’t think you have to be famous to be recognised.”
Mr Murray raised £600 for two plaques by donation. An exhibition about the Bombardment and World War One will open in a room near his museum, also today.
The shelling of Scarborough killed 18 civilians and hit Gladstone Road School, Scarborough Lighthouse, the Grand Hotel and the castle.
The Bombardment also claimed the life of 14-month-old John Shields Ryalls;
His death led Winston Churchill, then First Lord of the Admiralty, to call the Germans “baby killers’.
Leonard came from a large but poor Scarborough family who had moved during the mid-19th century away from the agricultural villages to the town in the hope of a better life. He was married with three children. His third child, Maggie, was born in 1901. Sadly, she only survived for a few months. This, and complications during the birth, led to the death of Leonard’s wife.
Leonard was buried in Dean Road Cemetery in the same grave as his wife and child.