Geoff Willis was an unexpected attendee at last week’s formula one test at Jerez.
The Briton, formerly one of the sport’s prominent technical figures, mysteriously left Red Bull in the middle of last season.
He has also worked with Williams and McLaren, and more recently was ousted from his position at Honda.
There was speculation late in 2009 that he could return this year with Ferrari or Sauber, but the Swiss camp earlier this month said its technical team will continue to be led by Willy Rampf.
Rumours are now linking the 50-year-old with the new Spanish entrant Campos, or its Italian car constructor Dallara.