Thank you all for your kind responses (the only ones I have received after posting in various forums).
Shell Management - I will certainly look into that - thank you for the tip. I had been in touch with Vernon Scannell's widow (He wrote Winged Shell) who informed me that she thought her husband had said much of the Shell archive stuff was put in a skip in the early 1970s. I was asking about the Airwork operation related to Shell in Ecuador (late 1940s/early 1950s) at the time. I will certainly get in touch with them though.
Many Thanks again
KeMac