Late starter Easton, who knows this place well having spent his wedding night at the resort overlooking the famous town of St Andrews, opened with a bogey at the 10th - his first hole - before making amends with birdies at the 12th, 13th and 15th.
It was the opposite for Sharvin, who found himself two under after 10 holes but carded back-to-back bogeys and then a double bogey at the 15th to go over par, eventually signing for a 74.
Wallace is in a share of second alongside South Africa's Bryce Easton after birdieing his first three holes on his way to a seven-under 65, with Ryder Cup captain Harrington a further shot back alongside English trio Aaron Rai, Chris Paisley and Garrick Porteous.
The pair both shot level-par 73s in their second rounds at Studley Wood Golf Club in England which, combined with their level-par first rounds from the Oxfordshire, was not enough to qualify for today's final round, with the cut two under. "I putted really well, I also played very well from tee to green and felt confident and relaxed - 62 is really, really good".
Otaegui started like an express train, with birdies at the first three holes.
A further six birdies on the back nine ensured a memorable day for the world number 248, who added: "I felt like a good round could come".
"But the putting wasn't there".
A trio of Englishmen are not far behind, with recent European Tour victor Aaron Rai once again sitting pretty in the leaderboard after a 6-under par opening round, a score mathced by Garrick Porteous.
The former world number one said: "This golf course is set up for tourists I suppose and there's quite a lot of room".
He'd earlier talked about the Covid-19 protocols being different to those now in America, adding: "People are talking about comparing Europe with the U.S. and their bubble is far less restrictive".