There's only a little GT40 interest to follow, but it may help:
Ed Lowther, the guy in your pic, was a big friend of Doc Wyllie, whose Bobsy is also featured in these images. Ed was a very successful club and track racer, scoring successes with Corvettes for the
Gulf Oil Racing Team in the late 1950s and went on with his crew chief Ray Heppenstall to real success with Cobras, racing with Shelby and the John Wyer GT40s with Jacky Ickx, Dick Thompson and others. He also raced the Howmet gas turbine car.
Both Ed and Doc Wyllie raced in the Steel Cities region of the SCCA, along with Grady Davis (Vice President of Gulf). With pictures of Ed and Doc Wyllie's Bobsy, these photos could well have belonged to Doc.
Gulf sponsored Brabham in F1 for 1968 (Repco V8 engined cars) so I imagine this pic comes from that era. It's worth visiting the
Repco Brabham website for more info and an ID on the engines.
In F1, Gulf went on to sponsor Motor Racing Developments (1969) Bruce McLaren Racing (1969-71) and Yardley McLaren (1972-1973) (all Ford engined cars between 69 and 73).
They also sponsored McLaren in the Indy 500 from 1969-1974 and your top right photo looks like Johnny Rutherford's 1974 McLaren M16 Offy which won the Indy 500.
Tyler Alexander was McLaren's chief engineer in 1974. He was no more than a mechanic for McLaren in the late 1960s. Teddy Mayer and Peter Revson brought him over from the USA when they raced Formula Junior, and when Mayer helped Bruce McLaren form his racing team, he was taken on as a mechanic. Tyler is now special projects manager for McLaren-Mercedes.
The bottom right image is another of Gulf employee Doc Wyllie's Bobsy in its later years. Here's the best image I can find of the car when it was campaigned in the US. Note Doc's Gulf sticker and the Gulf Brabham colours of orange and green:
Cheers
Rob