Basilides believed that Jesus Christ was an incorporeal power that was unable to be crucified, not mentioned by Baigent, Lincoln & Leigh.

Quoting Irenaeus, from “Against Heresies”, I.19.2 (or 4)
Edited by James Stevenson (1957), Revised by W.H.C. Frend (1987), “A New Eusebius: Documents Illustrating The History of The Church To AD 337” (SPCK, 1957, SPCK, 1987):
“For since he (Jesus Christ) was an incorporeal power, and the Mind of the Unborn Father, he transfigured himself as he pleased, and thus ascended him who had sent him, deriding them, inasmuch as he could not be laid hold of, and was invisible to all.”

Alternative Translation:
“For since he (Jesus Christ) was an incorporeal power, and the Nous (mind) of the unborn father, he transfigured himself as he pleased, and thus ascended to him who had sent him, deriding them, inasmuch as he could not be laid hold of, and was invisible to all.”

Quoting “The Holy Blood and the Holy Grail”: