Oldest people in the 1939 register: (no-one born before 1835 listed)
John C Francklow born 1835, died 1944 North Bucks aged 109
Julia Cass born 1835, died 1939 Bridgwater aged 104
There is actually one person allegedly born in each of 1825, 1824 and 1821, so respectively 114, 115 and 118 years old. Even less likely is the person born in 1964 who would thus not be born until 25 years in the future! I suspect that the validation of data entered was less than thorough.
Other odd statistics: From 1836 there are 13 survivors, from 1837 there are 20. However if you search for 1838 or later years there are 170,000, even if you search for a range of years! Maybe it's a coincidence but 1838 is the first full year of civil registration, but how could this be relevant?
Of the 41 million persons supposed to be listed there are 4,095,901 born 1916-39 (so have been un-redacted). The 1951 census at
www.ons.gov.uk shows the number of people born 1916-39 was then 15,849,894, so probably 12 million of the 40 million people in the register are currently closed. It is possible to search using a last name of double quote (") and this seems to indicate there are 3.4 million records with no last name, although it's difficult to check as it's not possible to view results beyond the 100th page. Additionally there are 107,000 last names that begin with a question mark, so that looks like a possible further 3.5 million records that will never be found on any conventional search by name. Then there are the records with question marks within the name and names that have been mis-transcribed, it's a wonder anyone can be found at all. My uncle Cuthbert was listed as Catherine and female, though fortunately could still be found as his birth date was correct.