Thanks all for the rapid replies!
Atilio was killed in action around December 1917 so the guy who died in the 1960s is definitely not him. Thanks, Max!

Suzard: you've got exactly the right man. I actually have that particular piece of info saved in Ancestry but I just cannot trace his military career, short though it was.
CaroleW: No, I haven't checked Freebmd - thanks for that suggestion. I will now be able to try to find Umbarto Attilio Locatelli thanks to your efforts. I'm sorry but I don't understand MRI? Also, thank you for checking the CWGC listing.
We do know that he was killed in action/died somehow during the war because his daughter remembered that she was 6 when he died. That would have made the date between 1916 and 1917, as Anita was born in May 1910.
His grand-daughter (my cousin for whom I'm doing the research) has two Italian medals: the Medaglia dell Guerra and also the Widows medal which was obviously issued to Angele Locatelli. It's interesting that he was awarded both Italian and British medals, yet my cousin does not seem to have the British ones.