Wonderful subject, Tracy! Lights was a fascinating, and feisty, fellow. And he did/does have a grandson, A.T. Lightoller, whose autographs can be found for sale on eBay. A.T. became commander of the British submarine HMS Rorqual. I have a cheaply-bought video of a BTS convention that includes an interview with a grandson of Lights who might be A.T. -- Geoff would surely know better. At any rate, he reminisces about how Lights taught him how to sail; sounds like when it came to matters nautical, Lights could be quite the taskmaster!
I heartily recommend the book Mike H. mentioned, variously known as "Titanic Voyager" and "Lights: the Odyssey of C.H. Lightoller", which tells a wonderful tale of how Lights met his wife. She had a physical disability, which didn't trouble him in the slightest: during the voyage, he gallantly carried her all over the ship. That particularly endeared him to me.
The book also recounts some very funny incidents, of Lights "skating" across the slippery bridge of the Oceanic (and colliding with the Captain), and setting off a cannon in Sydney harbor and raising the enemy flag, a stunt which could have cost him his career.
The Dunkirk story is in there, too, and it's amazing. Between Lights and his son, they managed to squish over 100 soldiers into Sundowner for evacuation, completely astounding those in charge. (Rather like the old joke of crowding college students into a Volkswagen -- except that this was no joke, it was life-or-death.)
Of course, Lights' autobiography is a masterwork (which I'm now able to read thanks to an "angel" who shared it with me
). He was quite something...
All the best -- Susan