The 10-man home team will be without highly rated 18-year-old Sam Horsfield. The Florida-based player, who became the youngest Briton to qualify for the US Open earlier this year, withdrew last week citing "personal reasons".
Of the line-up that will compete for the amateur version of the Ryder Cup, only Ashley Chesters, Cormac Sharvin and Paul Dunne are higher than Horsfield in the world rankings.
"It was a great surprise and extremely disappointing," Edwards told BBC Sport before the contest against the United States, who will defend the famous trophy at Royal Lytham this weekend.
At his last meeting with Horsfield, Edwards was struck by the youngster's apparent enthusiasm for the contest. "When I went to the US Amateur, all the talk was 'when are you announcing the team', then to be told he isn't coming is disappointing."
Edwards says he received no elaboration on why the Manchester-born student decided to pull out. "No, that's it - just personal reasons," he said. "Very strange, yes. I can't add anything."
However, the home skipper is convinced Horsfield's absence will not weaken his side's bid to wrest back the trophy they last won at Royal Aberdeen four years ago. "We have a great replacement in Ewen Ferguson," he said.
"Ewen is a former British boys' champion, a winner twice this year in Scotland and part of the winning Scottish team at the European team championships.
"He will love the Walker Cup. It was a very tough phone call to make to him, actually, when I had to tell him originally he wasn't in the team."
The Americans are favourites and boast a side that dominates the amateur standings. World number two Maverick McNealy, 19, is the highest ranked player in the match and one of six US players in the top 10.
That list also includes the recent US amateur champion Bryson DeChambeau, 21, who is also a National Collegiate Athletic Association individual champion. The team, captained by John 'Spider' Miller, features Jordan Niebrugge, who finished sixth at The Open earlier this year.
"Clearly they will have 10 good players but that just makes the challenge even greater and something more to relish," said Edwards. "We will be inspired to perform against them."
Great Britain and Ireland also boast a couple of players who excelled at St Andrews in July, with third-round leader Dunne and Chesters, who was 12th.
"I'm sure they will have learned a lot from those experiences," said Welshman Edwards, who leads the team for the third match running.
"The more used you are to playing in front of crowds, the easier it does become.
"I'm sure the other lads will feed off that and take great confidence from it."
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Dunne is one of a record five Irish players in the home team. "These Irish lads have been together for some time now, playing boys' and men's golf for the last four or five years. One drags another along, don't they?" Edwards said.
Inevitably, Walker Cup teams are also shaped by the churn of players turning professional. The Americans are without Oliver Schneiderjans, and amateur champion Bradley Neil gave up a likely place in the home team after deciding to join the paid ranks.
"I've no issue with anyone turning pro because of the rewards out there - but I do have an issue with the timing of some of them," said Edwards, who is director of coaching for England Golf.
"From my perspective with the England team, since the last Walker Cup we've had 20 either England squad or age squad players turn pro.
"It's a great shame, I don't think the players are appreciating the value of experience.
"You've only got to look at the very best players. OK some don't stay in amateur golf very long, but look at Tiger Woods - three US junior amateurs and three US amateurs. Who can argue with that?
"If you get used to winning that really helps your transition. The age of players turning pro in the last few years has gone down, I'm guessing, by a couple of years.
"The game has to do something because there's not enough room on the pro tours for them all to make a living."
That said, Edwards is more pre-occupied with the forthcoming hostilities. As a player back in 2003, the Welshman completed a famous GB and I victory at Ganton.
Four years ago he skippered them to success over an American side that included Jordan Spieth, Harris English, Russell Henley and Peter Uihlein - and Edwards believes another victory is within the compass of his 2015 side.
"I've got a really good feeling about this team," he said. "They've gelled really well, we are looking forward to getting going. We know the golf course.
"They all sense it, this is a great opportunity for them to create history and become not just a Walker Cup player but a Walker Cup player in a winning team."
Despite disappointment at the withdrawal of his fourth highest-ranked player, Great Britain and Ireland captain Nigel Edwards is confident his team can regain the Walker Cup this week.