Uncapped Harlequins wing David Strettle has been summoned to join preparations for England's RBS 6 Nations showdown with Ireland after Jason Robinson suffered a neck injury in training.

Sale Sharks star Robinson, who has scored three tries in this season's tournament, could be a doubt for the Croke Park clash.

He is being treated by England medical staff at the world champions' Bath University base, with his condition to be reassessed today ahead of departure for Dublin.

Head coach Brian Ashton has called up 23-year-old Strettle, a key performer in England Saxons' victory over Italy A this month, as precautionary cover.

England assistant coach Mike Ford said: ''Jason got a bit of a knock and has gone off to see the doctor. Hopefully, he will be okay.''

Robinson, capped 41 times, skippered England on their last Dublin mission two years ago, which proved his final Test match before coming out of international retirement for this season's Six Nations tournament.

If the 32-year-old is sidelined, then Ashton would probably promote Newcastle back Mathew Tait from replacement duty, although a full Test debut for Strettle could not be ruled out.

As Ashton awaited developments, news filtered through to the England camp that another 2003 World Cup winner, Steve Thompson, will miss the title defence in France later this year.

The 47 times-capped Northampton hooker will undergo surgery next week on a neck injury which has already ruled him out of Six Nations contention.

Thompson has a disc problem in his neck which creates a loss of feeling down one arm. A month ago, the Northampton and England medical teams agreed he required an eight-week rest from playing and training.

The plan had been to reassess him after that but the decision has already been taken that Thompson requires an operation.

Saints head coach Paul Grayson said: ''We are all so disappointed for Steve and we will be working hard with him to help his recovery.

''We look forward to his invaluable support behind the scenes while he recuperates.''

Leicester's George Chuter, who currently holds the England number two shirt, added: ''I hadn't heard about Thommo.'

''I get on very well with him - he is a nice guy who has been a great servant to English rugby.''

Thompson has been suffering on-going neck trouble, but took a heavy blow during his last game for Northampton, the 17-8 Heineken Cup defeat to Biarritz almost four weeks ago.

He now faces an anxious wait to discover whether or not the injury will end his career.

While England wait for an update on Robinson, Ford underlined the threat posed by Ireland's celebrated midfield pairing of Brian O'Driscoll and Gordon D'Arcy.

O'Driscoll has recovered from a hamstring problem that meant he missed the 20-17 defeat against France this month.

His partnership with D'Arcy poses arguably the biggest danger to an England team targeting a first Dublin victory since 2003.

Ford added: ''We knew Brian would be fit, so we have been planning to counter the threat.

''O'Driscoll is the top try-scorer in Irish international rugby history, and his record speaks for itself.

''As a defensive coach, it is D'Arcy, really, who worries you the most. He has great acceleration off the mark; he can step off both feet and he really is the catalyst for Ireland to go forward.

''At the moment, Brian is playing a kind of support role to what D'Arcy is doing. They are both great players.''

Ford spent four years as Ireland's defence co-ordinator - his chief role with England since last May - and has questioned their ability to cope with being favourites, a mantle they hold going into Saturday's encounter.

Ford said: ''During the four years I was there, they got labelled as a team that couldn't handle the favourites' tag, and they didn't do that against France a fortnight ago. They are the favourites again this week, so there is a lot of pressure on them to win this game at Croke Park."