World marathon record-holder Paula Radcliffe was withdrawn from the team on medical grounds, with Scotland's Freya Murray the nominated reserve.
She will become the 55th Scot in the 2012 squad (and fifth in athletics) subject to approval from the International Association of Athletics Federations (IAAF) and the International Olympic Committee, as is the protocol for late additions.
Darryl Seibel, head of communications for the British Olympic Association, confirmed Edinburgh's Murray as the reserve and put approval "somewhere in between" a rubber stamp and a wing and a prayer.
UK Athletics lawyers have instructed Murray to say nothing. "We don't want it to look as if we are trying to bounce the IOC into a decision," said a spokesman.
The Tyneside-based athlete is more fortunate than her predecessor. Four years ago Kilbarchan's Hayley Haining was understudy to Radcliffe but was left in limbo as Radcliffe kept her own counsel before deciding to run.
She would wish to avoid the criticism that attended her then, and I understand it may have been different this time.
Radcliffe has a foot problem and underwent a fitness test yesterday. It concluded she would not be competitive.
Her only race this year was a half-marathon in April, and since Beijing she has run only three marathons, the most recent in Berlin last September.
Radcliffe issued an emotional statement which struggled to avoid a career valedictory note.
"From the day when it was announced that London had won the bid, taking part and performing well in the London Olympic Games has been a major goal in my life," she said. "The goal of a fifth Olympics in my home country . . . what better?
"The chance to make amends to myself for bitter disappointments at the previous two Olympics – through a lot of tough times it has kept me fighting, motivated and focused. That is why it hurts so much to finally admit to myself that it isn't going to happen. My sport is a beautiful sport, it gives so much fun and enjoyment . . . the downside is that it can break your heart and spirit many times over when your body is simply unable to match what your heart and brain want it to do."