Only a week ago, Williams was quoted as saying he had no desire to add to his 76 Test caps and return to the international arena.

But new coach Warren Gatland has persuaded the Cardiff Blues flanker to perform a surprise u-turn - and he has today been included in a 28-man Wales squad, to be captained by Ryan Jones.

Williams’ inclusion highlights the paucity of open-side flankers available to Gatland.

Robin Sowden-Taylor, 25, is seen as Williams’ eventual replacement but cannot currently command a regular place in the Blues side.

Gatland said: “We have had to mix the short-term and the long-term view and Martyn in particular is covering a specialist position.

“I talked to him this weekend and told him we wanted to select him and he took a couple of days to think it over.

“We have some good youngsters coming through, but the likes of Robin Sowden-Taylor are only going to benefit from having Martyn around at the moment.

“We feel he still has a lot to offer and we are delighted he has accepted the invitation to play for his country again.”

In the end, Williams was only retired for one game - Wales’ 34-12 November defeat to world champions South Africa at the Millennium Stadium.

Prop Gethin Jenkins was named captain for that game - but Gatland has given the responsibility to Jones.

Jones missed the World Cup with a shoulder injury but has returned to action for the Ospreys and performed particularly well in their Heineken Cup win over Gloucester at the weekend.

Gatland also dropped a hint that Dwayne Peel is under major pressure from Mike Phillips to keep hold of the scrum-half jersey after explaining he was overlooked for the captaincy because of the competition for places.

Stephen Jones was not considered for the same reason, indicating James Hook is being seriously considered as the starting fly-half.

Gatland said: “We have gone for Ryan Jones as captain and he is back, fit again and playing well. His ability is unquestionable on the pitch and he has the necessary experience to fill the captaincy role.

“I don’t mind admitting we looked at a number of players for the role and Jonathan Thomas in particular is someone who stands out as a key leader and a possible captain for the future, as does his Ospreys colleague Alun-Wyn Jones.

“The likes of Stephen Jones and Dwayne Peel will also be important leaders for us, but the competition for places in their positions probably ruled them out of that particular race at this time.”

Peel has been included in the squad but is an injury doubt after missing the Scarlets’ Heineken Cup defeat to Wasps yesterday with a shoulder injury.

There is no place for Newport Gwent Dragons loose-forward Colin Charvis or full-back Morgan Stoddart, who made a try-scoring debut against South Africa in November.

Wales squad for the RBS 6 Nations Championship:

Backs: Lee Byrne (Ospreys), Jamie Roberts (Cardiff Blues), Tom James (Cardiff Blues), Mark Jones (Llanelli Scarlets), Shane Williams (Ospreys), Tom Shanklin (Cardiff Blues), Sonny Parker (Ospreys), Gavin Henson (Ospreys), James Hook (Ospreys), Stephen Jones (Llanelli Scarlets), Dwayne Peel (Llanelli Scarlets), Mike Phillips (Ospreys), Gareth Cooper (Gloucester).

Forwards: Gethin Jenkins (Cardiff Blues), Adam Jones (Ospreys), Duncan Jones (Ospreys), Rhys Thomas (Newport Gwent Dragons), Huw Bennett (Ospreys), Matthew Rees (Llanelli Scarlets), Ian Evans (Ospreys), Ian Gough (Ospreys), Alun-Wyn Jones (Ospreys), Jonathan Thomas (Ospreys), Martyn Williams (Cardiff Blues), Robin Sowden-Taylor (Cardiff Blues), Gareth Delve (Gloucester), Alix Popham (Llanelli Scarlets), Ryan Jones (Ospreys, capt).