After playing for
Western Heights High School First XV, Shelford was selected for the
Bay of Plenty Secondary Schools and Auckland age grade sides, and made his
Auckland provincial debut in 1982. Shelford enlisted in the
Royal New Zealand Navy as a physical training instructor (PTI), and during this time also played rugby for the Navy team. In 1985, when the
North Harbour Rugby Union was created, he moved with it as his club side was a member. This was the same year he was first selected for the All Blacks, for the later abandoned South Africa tour. Shelford's first game for the All Blacks was against
Club Atlético San Isidro in Buenos Aires on 12 October 1985. He then joined the unauthorised
Cavaliers' tour of South Africa in 1986, which included 28 of the 30 players selected for the original tour. Shelford made his Test debut for the All Blacks later that year against
France in a 19–7 victory in
Toulouse, and then was a notable victim of the infamous "Battle of Nantes" in the second Test. Roughly 20 minutes into the match, he was caught at the bottom of a rather aggressive
ruck, and a French boot kicked his groin, ripping his
scrotum and leaving one testicle hanging free. He also lost four teeth in the process. After discovering the injury to his scrotum, he calmly asked the physiotherapist to stitch up the tear and returned to the field before a blow to his head left him concussed. He was substituted and watched the remainder of the game from the grandstand where he witnessed the All Blacks lose 16–3. In 1987, the first
Rugby World Cup was held in New Zealand. Shelford played in five of the six All Blacks games and was a member of the team that won the final against France 29–9. He was involved in an incident during the semi-final match against
Wales that saw
Huw Richards become the
first player to be sent off in the tournament. Richards punched the All Black lock
Gary Whetton after a loose scrum and Shelford reacted in defence of his teammate, landing a blow that knocked Richards to the ground. Shelford escaped punishment while Richards left the field. Shelford took over as All Black captain after the World Cup, first captaining the side during the 1987 tour of Japan. During his captaincy from 1987 to 1990, the All Blacks did not lose a game, only drawing once against Australia in 1988. Upon becoming captain, Shelford brought his teammates to
Te Aute College, a Māori school, to see the students perform a traditional
haka. Although the All Blacks had been performing the
haka at the start of their matches since the team's inception, it was Shelford who taught them the proper way to perform the "
Ka Mate"
haka. Shelford has said that the All Blacks had previously done the
haka in a way that showed little understanding or training, and with the support of a former All Black,
Hika Reid, stressed the importance of correctly learning the
tikanga, words and actions, noting that the key was helping the European members of the team to embrace the change. The All Blacks performed the
haka for the first time in New Zealand at the
1987 Rugby World Cup. In 1990, the All Blacks' selectors decided that Shelford was not up to the standard for the team and he was controversially dropped after the test series against
Scotland. The general public were unhappy with this decision, especially when the All Blacks lost the third test of their next series against Australia, ending a 17-test winning streak (and 49 game streak including non-tests). After this, fans started appearing at games with signs saying "Bring Back Buck". Shelford said he had "no hard feelings" about being dropped and that he had spoken with the then selector,
Alex Wyllie, who expressed a "few regrets" about his decision. and coached for some time in Britain, including spells at
Saracens and
Rugby Lions. He returned to New Zealand and was the assistant coach of the
North Harbour team in 1997 and coach in 1998. Currently, Shelford is coaching at his former club, North Shore in Devonport. In 2020, he became the host, assistant coach and emergency player for All Blacks Alumni in
Match Fit, a reality documentary series to train retired All Blacks back into shape against the current New Zealand
Barbarians squad of former internationals. He reprised the role in 2021/22 (aired 2022). ==Honours==