As Campaign went to press, Lou Burrows, Grey's human resources consultant, was waiting to meet with police officers to view security camera tapes from an internet cafe identified as the source of the e-mail.
Inquiries so far have established that the e-mail was sent from an internet cafe in London's Tottenham Court Road on the afternoon of Saturday 7 February.
Lace financed the hunt for the terminal that sent out the e-mail out of his own pocket.
The footage was relatively easy to secure because internet cafes are currently being monitored by security cameras owing to the heightened threat posed by Al Qaeda terrorists, who are known to use internet cafes for their communications.
Lace has denied claims in the e-mail purporting to have been written by him and sent to industry figures. It claimed that he was leaving to set up a loyalty scheme with the Air Miles managing director, Drew Thomson.
Thomson and two others named in the memo as being party to the plan, Nicola Mendelsohn, the Grey marketing director, and Peter Walker, BBDO Europe's former finance chief, have also denied involvement.
Lace refused to comment on developments, although Grey sources indicated that "significant progress" was being made in the police investigation.
Lace is understood to have repeated his insistence that there is no substance to the e-mail's claims in conversations with Carolyn Carter, the president of the Grey Global Group for Europe, the Middle East and Africa, and Ed Meyer, the Grey chairman.
Meyer said: "I try to believe in the goodness of people until proven otherwise. There will be an investigation - Garry deserves it."
Carter is leaving Lace to lead Grey's attempt to unmask the culprit.
"We have no tangible evidence at this point to change our view of Garry or his team," she said.
- Opinion, p21.