I couldn't find anything on a second marriage, but company records for "Anthony Archer-Wills Ltd" give her (res. Petworth, W. Sussex) as "Ms" rather than "Mrs", where a Kathryn Lynn Archer-Wills (given her age, presumably Anthony A.-W.'s wife) is listed as "Mrs". Is "Ms" ever used for widows/ divorcees? I'm not very familiar with it.
Electoral roll records gave a Norah E. Messenger as resident with a Douglas B. Messenger at Eastleigh, Hants. in 2002 and 2006, but I found a 1951 marriage between D. B. M. and Norah E. Holwill (and her 1926 birth record) which put paid to that tentative conclusion.
However, there is also a 1961 marriage at Worthing, W. Sussex [n.b.- not far from Petworth, the address from company records as above] for a Norah E. Windham and Edwin Messenger, and no birth record for a Norah E. Windham, which possibly suggests an intervening Strutt/ Windham marriage(?) The Edwin Messenger b. 1889 who d. 1970 at Worthing [probate gives address as Stile House, Gay Street, Pulborough] would appear to be this man, but given the format of probate records of that time, no mention is made of a widow.
EDIT: Aha, the "Interior Designers Handbook" (1987), p. 192 gives "Anthony Archer-Wills, Stile House, Gay St, Pulborough, Sussex", which corroborates the above tentative conclusions; where the "Windham" came from I have no idea, but it all seems to fit otherwise. Grade II-listed 17th-century ("or earlier") Stile House also known as Stile Place Farmhouse).