Probyn was fairly slight for a modern international prop, and a good part of his effectiveness can be explained by his unusual physique: his bony shoulders sloped at a sharp angle, and his hips were widely set.
Due to Probyn's scrummaging techniques some players took to cutting off the sleeves of their shirts as they believed this was how Jeff managed to get so low down in the scrum and would use the sleeves as leverage. After Probyn continued to keep the scrum incredibly low, it was evident that their sleeve cutting was unnecessary.
After retirement from playing, Probyn was a member of Club England, the Rugby Football Union Committee. He was the manager of the England U21 team from 1994 to 1997 during which time he introduced Clive Woodward and Andy Robinson as coaches to representative rugby. After managing the U21 teams tour of Australia, where they played as a warm up for the first ever Cooke cup game between England and Australia, he returned to the RFU council and sat on the Club England group that elected Woodward as England coach. He sat on the 2006 review that saw the replacement of England's world cup winning coaches with the current team, led by Martin Johnson.
After leaving the RFU, Probyn was critical of cross-code transfers, such as that of Andy Farrell.
He also formed The Front Row Union Club F.R.U.C with fellow international front-row forwards Brian Moore and Paul Rendall.
Probyn is an Honorary President of Wooden Spoon, the charity of British and Irish rugby.
Probyn is also a regular on talkSPORT as their expert on Full Contact.