Both my son and my daughter have reported that when giving their name, it has been repeated back to them as “Quinton” rather than “Pointon”, and this has twice happened to me recently. Neither name is particularly common. What we have here is surely a synchronic example of the diachronic development of one of these sound complexes into the other, as is postulated for one of the differences between P-Celtic and Q-Celtic (Welsh pedwar and pump – ‘four’ and ‘five’ – versus Irish a ceathair and a cúig, for instance). The reconstructed Indo-European *kw developed into Latin ‘qu’ – quattuor and quinque, but into Germanic ‘p’ and then ‘f’ (English four, five, German vier, fünf). Celtic went both ways. I think it is interesting that a mis-hearing of an uncommon word can lead to the same development today.
Both labial and velar consonants are [+grave] in the Jakobson and Halle system of distinctive features (they have more energy in the lower frequency range), as do the back vowel that immediately follows in both Pointon and Quinton, and this is taking priority over the compact vs diffuse feature that distinguishes labial and alveolar consonants – and high vowels (+compact) – from the velar consonants and low vowels (+diffuse).
This is the same feature that ventriloquists take advantage of when they say ‘gottle of geer’ for ‘bottle of beer’ to disguise the fact that it is they rather than their dummy that is speaking.