Luke Mercaldo

Hi all, I am reading a well written book,”Marked for Death” by James Hamilton-Paterson. On page 189 he describes Captain Hawker’s VC winning combat in July 1915. He states that Hawker’s Bristol Scout had a fixed mounting for his single shot cavalry carbine. I have seen this same statement before – is it true that he used a single shot carbine in his VC winning combat with 3 EA? If it is where is the source for this information?