Seeing this thread reopened represents something of a mixed blessing, since on past form a lot of firefihting is going to be required again.

The OP's post at 04.40 on January 3rd contains several highly questionable statements:

The material tended to say as much about the ideological perspectives of those writing it as it did about Pardon himself. This applies to Mike Yates' use of a Marxist approach for one essay... Put briefly and simplistically, and following Hillery, the ideology in question could be described as that of the 2nd UK folk revival.

For a start, the ideology of the 2nd folk revival - at least in it's approach to traditional song - owed more to Cecil Sharp than Karl Marx, so it's not valid to skate between the two as though they were one and the same. At no point has it been shown that research into WP's singing owes anything to Marxism, other than a couple of references to a Mike Yates article not actually quoted, and the fact that MacColl and Lloyd were Marxists, so well... it's obvious, innit?

There were contradictory or unclear ideas about, for example, the sources of his songs and about whether he 'preserved' the tunes by playing them on his melodeon or whether, due to the musical limitations of that instrument, he changed them, this explaining how come his tunes were different at times from those traditionally used for the songs in question.

A melodeon is limited in not being fully chromatic, and in its limited range of keys. Neither of these would prevent me from picking out the melody of pretty well any song from, say, Sharp's collection, or 'The Voice of he People' on the instrument, since folksong melodies characteristically use simple scales. It's also not valid to compare WP's tunes with those 'traditionally used', since one of the defining characteristics of traditional song is melodic variation: there is no single 'traditional tune', and most of WP's are recognisable as variants, albeit often particularly interesting ones. WP may of course have mis-remembered these melodies, but the same could apply to any singer of orally-learned material.

The methods used by some of those investigating Pardon did not seem to me to be rigorous: there was use of leading questions, for example.

This claim has been made repeatedly over the course of this thread, but no examples have been quoted, and no appropriate analysis made of the reasons why the research is unsatisfactory. It's not academically acceptable merely to make a statement on the basis of a vague impression gained from unquoted material. Elsewhere the OP expresses dissatisfaction with interviewing as a valid technique, without suggesting an alternative method for finding out the singer's background, motivation method of learning songs, etc. What would be preferable - a Rorschach Test?

he is said to have learned his songs 'the traditional way', though how far even that is true seems questionable, given his own assertions that he did not sing them at the time.

Apart from the fact that he did sing 'The Dark-Eyed Sailor' at the time (and was certainly not unique as a traditional singer in having one song that was his recognised property for public occasions), whether he sang them or not in the period between learning them from family members, and performing them many years later, has no bearing on the the question of whether he learned them 'in the traditional way'. Some of the best-known recorded traditional singers were regular performers in pubs, singing competitions, etc, but many others were racking their brains for half-remembered fragments from their youth, at the behest of a collector.

One last question I can help with:

Just out of curiosity, does anybody know which Union, if any, was Pardon a member of? I ask because I have seen his 'trade unionism' lauded, yet Hillery describes him as a self-employed small businessman

On November 9th, Jim Carroll posted:

"Walter was very proud of his family’s association with the early Agricultural Union movement. When George Edwards restarted the Agricultural Workers Union in Norfolk in 1907, the first one started by Joseph Arch in the late 19th century having folded, Walter’s father Tom had the second Union card issued, Nos.1 and 3 going to men from nearby villages. Forty years later, all three men were awarded silver medals for their services to the Union. Walter learnt a number of songs, parodies and rhymes connected with the Union..."

Happy to be of assistance.