Hi Lucky13, in an attempt to answer your question, Whitleys of Nos, 10, 51, 58, 77 and 102 Sqns were engaged in attacking targets in Genoa and Turin in mid 1940, the first of which was made on 11 June. These aircraft flew south from the UK to the Channel Islands, where they refuelled, then headed inland and flew over the Alps. At the time the raids were regarded as considerable feats of endurance. The Whitley V had a range of around 1,650 miles with a 3,000 lb bomb load; the V was powered by two 1,010 hp Merlin Xs. I hope this helps.
There's a thread elsewhere here where a chappie had some propaganda leaflets from one of these raids and wanted information about a particular aircraft that was shot down.