Which 428 Frua fastback did Rob Walker own...?

[SunDude]

AC Heritage (Weybridge U.K.) is currently restoring an AC 428 Frua fastback that had been converted into a 427 Cobra roadster around 40 years ago.

They claim this car was previously owned by Rob Walker, but I can't find any information that he ever owned a fastback. The 428 Frua convertible that Walker once owned (CF14) still exists in its original form, and was offered for sale on Bring a Trailer back in Aug 2023.

Does anyone know which CF chassis "Cobra" is being restored by AC Heritage? Which 428 Frua fastback did Rob Walker own?

See photos of the "Cobra" restoration here: www.instagram.com/p/Cygu1t4olXk/?utm_source=ig_web_copy_link&igshid=MzRlODBiNWFlZA==

CF14 on Bring a Trailer (DNS): www.bringatrailer.com/listing/1968-ac-428-frua-convertible/