Hello,
There was no "Henry Atkinson" on board the Lusitania and no rating of First Class Officer on the Lusitania. My first instinct was that this person might be Mr. Henry Adams, a 56 year old first class passenger whose body washed ashore and was numbered 237. His wife of one month, a Canadian, survived the disaster, but lost her senses due to the trauma of the sinking. She died not long after in an asylum. I believe that the person mentioned in 1933 was a recollection of a name over heard 18 years prior as there was no easy way to access the Cunard records as we can today. Hope this helps in your endeavour.
Brian