Popular myth would have it that Twm married, by clever design, Joan, daughter of Sir John Price of the Priory, Brecon, known as the heiress of Ystradffin. Apparently, Twm was in his seventies when he married, and that Joan was the wealthy widow of the previous Sheriff of Carmarthenshire, a post that Twm took up after his marriage, also becoming the local magistrate.

The irony of Twm becoming a member of the ruling classes to which he had previously been seen to rebel against, would add the finishing touches to a typical 'rags to riches' story, and nowadays, would be exposed by the media as a sure sign of hypocrisy and turning his back on the people he was once seen to represent.

Many stories of his life - some more true than others - were collected together by the historian Meyrick, in his 'History of Cardiganshire' 1810, and were developed further, increasingly out of context, by W.F. Deacon, in a sketch called 'Twm John Catty, the Welsh Robin Hood', included in the 'Innkeeper's Album', 1823, and in a play by the same author, entitled 'The Welsh Rob Roy'. Twm's adventures also featured in what has been described as the "first Welsh novel in English" - 'The Adventures and Vagaries of Twm Shon Cati' by T. J. Llewyln Pritchard in 1828, which was popular enough to have been pirated in the mid-19th century.

After his adventures, it is said that Twm fled to Geneva in 1557, returning two years later to receive a Royal Pardon on 15th January, 1559, which excused all of his previous misdeeds and criminal activities. Whilst it is accepted by most historians that the stories surrounding his youth are embellishments on a past that included banditry, man and myth divide after Twm's pardon in 1559.

The later years of Jones's life were devoted to the study of Welsh history and literature. He appears to have been employed by the chief Welsh Gentry in Cardiganshire to draw up their pedigrees or family trees. Heraldry, was a little known science and seen as somewhat occult, often resulting in Jones being described as a powerful magician. The ability to research and produce pedigrees would have put him in an influential position, as a pedigree was a document of great importance for those families who wanted to prove their heritage and status.

A number of his works on heraldry and family pedigrees have survived, preserving a detailed history of the families of Cardiganshire and forming a notable contribution to Welsh Tudor history in general. Many of his poetic works were published, copies of which are held at the British Library, and he is said to have been present as an ordained bard at an Eisteddfod held at Llandaff in 1564.

His early escapades earned him considerable notoriety, the memory of which formed the basis of the popular and traditional representation of him as Twm Sion Cati - the bandit. Myth aside, Thomas Jones, the man, secured a more respectable reputation as a Justice of the Peace, landlord, poet and historian, noted for his knowledge of genealogy and heraldry, and was described by his contemporary, Dr John Davies Rhys, as, "the most celebrated, accomplished and accurate herald-bard of the day" (Rhys, 'Welsh Grammar' 1592).

Despite the many poems, stories and plays written about Twm's exploits, he has never maintained the same degree of fame as his English counterpart, Robin Hood. No Hollywood films depict Twm's activities, and no tourist industry surrounds his birthplace. This may be because he didn't have any adventures involving Royal figures, or a supposed gentry background, as did Robin Hood.

It is possible, that because he was a real person with a documented history, the myths surrounding him could not produce a composite legend of the ultimate outlaw-with-a-heart, but could embody the multi-faceted man that he was.