Stone's England bid thwarted by back complaint
Stone bowled some of the fastest spells in county cricket last season, but he also suffered back trouble earlier in his career and England will be desperate to protect a player who has shown signs of developing into one of the most hostile pace bowlers in the country.
He had been selected in the group of EPP fast bowlers who will travel to South Africa for a ten-day training camp on November 11, before the fast bowlers link up with the rest of the EPP squad in Dubai towards the end of the month.
The fast bowlers camp in Potchefstroom has now been slimmed down to five players: Tymal Mills, of Sussex, who has expressed fears that injury may limit him to a future in T20 cricket, Jake Ball (Nottinghamshire), Craig Miles (Gloucestershire) and the Somerset brothers Jamie and Craig Overton.
It was a five-wicket spell against Kent in June that told of Stone's progress, with the Northants skipper Alex Wakely observing that he could not remember the wicketkeeper and slips ever standing so far back at their Northampton HQ.
Gregory had been due to attend the EPP batting and spin camp in Dubai from mid-November followed by playing for England Lions in the Twenty20 series against Pakistan A in the UAE in December.
Both players will now undergo rehabilitation programmes, working towards regaining full fitness for the start of the 2016 domestic season. No replacements have been named.