Several high-profile England players are set to miss this summer’s British and Irish Lions tour but the Wales centre Jamie Roberts is poised to be a surprise inclusion when Warren Gatland announces his squad to tour New Zealand on Wednesday. The experienced Roberts has leapfrogged a number of midfield contenders but almost half the English starting XV beaten by Ireland in the Six Nations last month are struggling to make the cut.

Established England players such as George Ford, Mike Brown, Jonathan Joseph, Joe Launchbury, James Haskell and Chris Robshaw are all likely to be squeezed out when the party is unveiled at midday, with Wales’s Sam Warburton captaining the squad for the second successive tour. Among the other England Six Nations winners poised to tour Argentina under Eddie Jones instead are Danny Care, Jonny May and Nathan Hughes.

Gatland clearly feels a different style of approach will be required to defeat New Zealand on home soil and Roberts has been a key member of the last two Lions expeditions. Wales, however, have latterly struggled for attacking sharpness and few expected the 30-year-old Harlequin to feature on a third Lions tour.

The selectors were still deliberating over the last couple of positions late into the afternoon, among them the merits of Dylan Hartley versus Wales’s Ken Owens. Hartley’s prospects appear slim but, with Steve Borthwick and Graham Rowntree both appointed to coach the Lions forwards, the Northampton hooker retains some influential support. He has been desperately keen to tour his native New Zealand, having missed the last Lions tour to Australia in 2013 through suspension.

Owens, however, was arguably the form hooker of the Six Nations and, while Hartley’s influential leadership during England’s record-equalling sequence of 18 Test victories cannot be entirely overlooked, the 31-year-old may once again be wearing a white jersey against the Pumas this summer.

Saracens, though, remain hopeful that both Jamie George and George Kruis will be picked, with their director of rugby, Mark McCall, already backing the Vunipola brothers, Owen Farrell and Maro Itoje as certainties. “I think there are definitely four who will go,” said McCall, whose side are preparing to face Munster in Saturday’s Champions Cup semi-final in Dublin. “We could be celebrating with some and commiserating with some others.

“Any of the players who say they are not thinking about it are lying. It’s going to be an unusual lunchtime for us because it’s a big training day but I’m sure everyone will be sitting watching the announcement. Fingers crossed that all our players who are expecting to go get the nod.”

Last time around in 2013 England eventually had 14 representatives while Wales contributed 16 and Ireland 12. The original squad contained 15 from Wales, three from Scotland, 10 from England and nine from Ireland. The former New Zealand and Lions coach Graham Henry has warned, however, that Gatland’s squad will be up against it from the start. “I just wonder if the itinerary is suicidal,” Henry told ESPN. “You need to ensure some momentum is created by results and you just wonder how they are going to go into the test series with that itinerary. It is very demanding.”

The Lions will open their tour in Whangarei on 3 June against a Provincial Barbarians XV.