Anyone familiar with World War I records may be disappointed by limited availability of equivalent service records for World War II; the records of Britain’s Army, Navy, and Air Force are still classified. Fortunately, many other collections can help.
If someone who served in the British Army was killed in WWII, they should be listed in the UK, Army Roll of Honour, 1939–1945 database. Through these records, you can discover death dates, ranks, regiments, theatres of war (France and Belgium, Middle East, or Africa), and the branches served in at time of death. This is a transcribed series of records, so there will be no original document to view, but you can save the information to your tree.
Another useful record set from WWII is UK, British Army Prisoners of War, 1939–1945. This database can can help you discover the ranks, regiments, and prisoner numbers of prisoners of war, as well as the locations and types of camps they were held in.
To find Jewish ancestors who survived the Holocaust, search the names of the over 60,000 people freed after the war in our Holocaust: Survivor names printed in Sharit Ha-Platah, 1946 database.
Although British military service records for WWII are still held by the Ministry of Defense, family members can write to the Ministry of Defense and apply to get copies of personnel records. If the soldier is still alive, you'll need his or her permission; if the soldier is dead, you'll need the death certificate and the permission of his or her next of kin.