[3] He carefully researched and catalogued the Italian paintings, many of which were documented in David Teniers the Younger's Theatrum Pictorium, though with incorrect attributions.

He first published his findings on The Gypsy Madonna and The Three Philosophers'[3] In the next eight years Wilde made more than 1000 X-ray photographs of works in the museum.

[3] After the Anschluss, the annexation of Austria into the German Third Reich on 12 March 1938, Wilde's Hungarian Jewish wife Julia was at risk.

With the help of friends including Count Antoine Seilern, the couple left Vienna for the Netherlands in April 1939 to visit an art exhibition; from there they flew to England, where they stayed at the home of Sir Kenneth Clark, director of the National Gallery and Surveyor of the King's Pictures.

Wilde soon went to Aberystwyth to work on Seilern's pictures, which had been sent to the National Library of Wales for safety at the beginning of the Second World War.