The seventh man in the Illustrious group is probably the Stoker 1st Class Gilbert Ernest Williams, service number 180919 (not 18019). CWGC says he died on 10 January 1941, so during the air attack that heavily damaged Illustrious.
The seven other men are all found in CWGC on 9 February 1941. My initial research was for "9 February 1941" and commemorated/buried on Malta, and returned no one. All seven sailors are commemorated on Plymouth and Portsmouth Naval Memorials. There are tens of sailors buried in Malta, so my guess will be that the mine explosion left no bodies to be buried, hence the commemoration on the memorial.
The best place on the net for Malta during WWII is IMHO the "Malta: War Diary" blog, but the above incident is not listed (
https://maltagc70.wordpress.com/2021...s-defenders-2/). Nothing on 8 or 10 February either.
The message Brian refers too can be seen in the Admiraly War Diary for 9 February 1941 on fold3 (
https://www.fold3.com/image/302516815), end of the page.
A former message (from VA Malta to CinC Med) is at the top of the page: "Explosion of 2 mines, 1 while being prepared for laying at RAF Station Hal Far, Casualties, Mines were near end of their safe life."