As the British and Irish Lions squad assembled at Dublin’s Carton House on Sunday evening a dark cloud was cast over the pending tour to New Zealand.

News breaking of Billy Vunipola’s withdrawal from the squad due to an ongoing shoulder injury dealt a severe blow to Warren Gatland’s ambitions of back-to-back Lions tour wins after his 2013 success in Australia.

Vunipola completed 80 minutes in Saturday’s Aviva Premiership semi-final – albeit his shoulders laden with strapping, but opted to pull out of his debut Lions tour with surgery set to take place before the Saracens No. 8 competes again.

Make no doubt, this changes things.

Saracens’ Billy Vunipola

Vunipola was one player Gatland simply could not afford to lose going toe-to-toe with the All Blacks.

Over the last year Vunipola has grown in stature and maturity, thrusting himself to the heart of England’s revival under Eddie Jones, starring in successive Six Nations crowns.

Present incumbent of the All Blacks No. 8 jersey, Kieran Read, has, for a significant period, been regarded a far superior player to any Northern Hemisphere back-row, but Vunipola is the one man who has bridged the gap.

Vunipola’s prime offering has always been an ability to notch up yardage, churn forward and leave would-be tacklers trailing in his midst. What’s changed is the reformed Vunipola does this for sustained periods, making him an invaluable game-changer. The growth has not only been physical, though; Jones has made him vice-captain of England and the 24-year-old has duly taken the enhanced responsibility, making better on-field decisions.

Vunipola has been fundamental to Saracens’ back-to-back European Champions Cup titles, producing a man of the match display in beating Clermont last weekend. Although unable to prevent Exeter Chiefs earning a Premiership final berth on Saturday, the powerhouse No. 8 was still arguably the best player on the field, despite Saracens’ hopes of a back-to-back double double being dashed.

Such has been Vunipola’s form he was rightly billed as instrumental to the outside chances of a Lions success. His absence puts a severe dent in not only prospects, but also resources.

One man’s despair, though, is anther’s opportunity as James Haskell has been drafted into the squad, but you have to say his chances of a Test berth are minimal.

Irishman CJ Stander was the lone candidate who would have wrestled Vunipola for the starting jersey, but Gatland will now consider a very familiar all-Welsh back-row of Sam Warbuton, Justin Tipuric and Ross Moriarty.