What a great day, in the Trad Calendar for England! But these two martyrdoms seem to me in many ways to signal the cultural end of the Faith S Augustine had brought from Rome to Canterbury.
John and Thomas, I think, were two of the commonest names in late Mediaeval England. S John's popularity may relate to the Wool trade (Ecce Agnus Dei ...) and was certainly helped by the massively powerful Merchant Tailors' Company, whose patron he was.
'Thomas' reflects, surely, the cult of our Blissful Martyr. 'Becket' may have been a word for the Cornish Chough ... which would be why Cardinal Thomas Wolsey put a couple onto his (very Tudorly messy) shield. He turned out to have nailed his colours to a very dangerous mast!
May Ss John and Thomas pray for the Holy Father, that he may regain physical health, and may resume the Petrine Ministry of safeguarding the Faith handed down through the Apostles, the Deposit of Faith.