I have come across what cannot be other than false age (certainly of year of birth) declarations in the 1939 Register and here I clarify that I have checked with the original image. For quite some time I have stood my ground on the actual birth dates in the Register, against one other Ancestry Researcher ( who points to others who agree with him) who argues, quite convincingly that the dates I show are absurd for the two parents of the ancestor we have in common. I will just quote the year and the given name for parents John 1874 and Ellen 1883. Yes there is no denying (or none I can dispute) that John's parents JT & ME were born 1864 & 1866 respectively. With Ellen's parents more plausible at 1863 & 1861. The general consensus is John was born 1891 (some 17 years different to the Register) and even Ellen at 1888 (5 years adrift).
In my mind there is no doubt whatsoever that the Register entry is for the right family, not only living at an address which is known to be correct by family, but correctly recording two sons, the elder being the common ancestor, born 1913 & his sibling 1914. We also know for sure that the elder child's birthday (the common ancestor) was indeed as shown in the Register.
There are birth registrations for John showing 1891 (not 1874), a marriage to Ellen in 1913 and the birth of their first child the same year. In the 1891 Census JT is 28 (1863/4) & ME 30 (1861) & their daughter Ellen aged 3 (1888). Which would all be nice were it not for contradictions of the Register. So using the Sherlock Holmes principle 'once you have discounted the impossible,whatever remains, however improbable, must be the truth' I fall back on research data, which in this case is quite probable.
So I ask myself why did the entry for JT show '74' and ME '83'? Could it be deliberate or a transcription mistake, remembering the facts will stand for considerable time and there are no signs of any amendments to the original script. It would make JT 65 instead of the more youthful 48, and ME 56 instead of 51. All very mysterious but for now I have but to agree with the general consensus based on other research and ignore the Register dates for both parents.