Rubuta ci gaba don wannan sakin layi - Fenwick ya buga wasan kwallon raga a matsayin ɗan makaranta don Caerphilly Grammar Technical School, kuma daga baya ya shiga Taffs Well RFC. A shekara ta 1971 ya koma Beddau inda ya buga wasanni 51 kafin ya koma kungiyar farko ta Bridgend. Duk da yake a Bridgend Fenwick ya sami dukkan wasanninsa 30 na kasa da kasa don Wales, inda ya fara bugawa Faransa wasa a 1975, inda ya zira kwallaye bayan minti biyar kawai, kuma ya gama wasan da maki 9. Ya kasance memba na 1977 British Lions yawon shakatawa zuwa New Zealand
, wanda ya taka leda a duka wasanni hudu. Ya kuma jagoranci Wales a wasan Centenary da All Blacks a 1980. Ya kuma buga wa Duniya XV a ranar 9 ga Agusta 1980 a Buenos Aires, ya yi rashin nasara 36-22.