What research tips can we gain from this story?
History books are generally written by the victors, those with a desire to record events from a particular political perspective, and those who seek to justify their own actions or self-promote.
All histories are affected by the personal experience and the views and attitudes of the author. For example many authors have a 'classical' education, concentrating on Greco-Roman, Egyptian or Renaissance cultures. There is often little mention of cultures such as the Sumerians, whose importance has only been recently recognized, or of Chinese, African, Indo or other cultures.
Verbal recollections, particularly of military service, are often glamourised, exaggerated or fabricated. Most military personnel are not on the front line but in administration and support roles. The real heroes tend not to boast of their exploits.
No author has access to all the relevant facts and thus any history is incomplete.
The quality of record keeping 100 years ago was not high. Because records were not accessible it was difficult to cross reference and identify errors.
Consequently it was easy for deliberate mis-statements to go unnoticed.
Documents were generally handwritten, often in copperplate script, making reading them difficult. Contemporary transcriptions inevitably contain errors.
Illiteracy was high. Thus many records (such as the census) were based on verbal recollections rather than documentary evidence.
Many children were illegitimate. Births were consequently not always registered. The fathers name is often not mentioned on birth certificates and illegitimate children might give false dates of birth to record a date after their parents marriage.
Military conscription was dependant upon age, and this could also affect the branch of the service or role one was assigned. Therefore the date of birth given to military authorities was not always accurate.
Giving false names on a marriage certificate does not necessarily invalidate the marriage.
A person may provide details on a form based on their recollection rather than reliance on a specific piece of evidence. This is often apparent when a relative provides details on a death certificate: it is common for the wrong date of birth to be given. Similarly a person may give an incorrect place of birth if they have never seen their birth certificate and simply recall growing up in a particular location.
If you are having difficulty tracing someone there are genuine reasons why a document may be inaccurate such as errors in the original, or as a result of transcription mistakes. However it may also point to a deliberate attempt to conceal the truth such as an illegitimate child, avoidance of conscription, criminal record etc.
When a person conceals the truth it is easy to jump to conclusions such as they were a spy. The real reason is often more prosaic.
In memoirs or in stories told to descendants there is a always pressure to overstate ones achievements and ignore unfavorable events. Genuine heroes rarely boast about their actions. All war memoirs should be taken with a pinch of salt.
It is always a good idea to look at surrounding entries on documents. The census will identify neighbours, who may be relevant. Baptism ledgers may identify related entries.
Even when you think you have found the person you are looking for do not assume you have got the right person. Continue to search in order to eliminate other possibilities.
Not all online databases are complete. Use different search tools. The free familysearch.org and freebmd.org.uk search tools are good starting points. You can download images from these sites that you need to pay for on other sites.
The UK government GRO registry office has a facility that displays the mothers maiden name on birth record searches. This is often not available on other geneology sites.
Various sites provide gravestone photographs. These can disclose important information not on the public record. They often have volunteers who will photograph a specific grave at no charge.
With thanks to Loli Menezes and Jane Grooms.
UK Birth Marriage and Death search.