G. H. Stokes), had departed Gibraltar on 11 December, to join the Mediterranean Fleet at Alexandria. By 8 December, the British had de-coded Italian C-38 wireless signals about the Italian supply operation and its course for Tripoli. The RAF sent a Wellington bomber on a reconnaissance sortie to sight the ships as a deception and on 12 December, the 4th Destroyer Flotilla, heading east from Gibraltar towards the Italian ships, was ordered to increase speed to and intercept. In the afternoon of 12 December, a CANT Z. 1007 bis of Regia Aeronautica spotted the four destroyers heading east at an estimated speed of 20 knots, off Algiers; Supermarina was immediately informed but calculated that, even in the case the destroyers would increase their speed to 28 knots, they would have reached Cape Bon around 3:00 AM on 13 December, about one hour after the 4th Division, so Toscano (who learned of the sighting while he was still in harbour) was not ordered to increase speed or alter course to avoid them. Following new Ultra decodes, a new reconnaissance plane was sent and spotted Toscano's ships at sunset on 12 December, after which the 4th Destroyer Flotilla was directed to intercept the two cruisers, increasing speed to 30 knots. This speed, along with a one-hour delay that the 4th Division had accrued (and that Toscano omitted to report to Supermarina), frustrated all previous Supermarina calculations about the advantage that the 4th Division would have. At 22:23 Toscano was informed that he would possibly meet "enemy steamers coming from Malta", and at 23:15 he ordered action stations. The 4th Destroyer Flotilla sighted the Italian cruisers near Cap Bon, at 02:30 on 13 December. At 2:45 on 13 December, seven miles off Cape Bon, the Italian ships heard the noise of a British plane (a radar-equipped Vickers Wellington, which located the ships and informed Stokes about their position), and at 3:15 they altered course to 157° to pass about one mile off Cape Bon. Five minutes later, Toscano suddenly ordered full speed ahead and to alter course to 337°, effectively reversing course; this sudden change disrupted the Italian formation, as neither Cigno (which was about two miles ahead of the cruisers) neither Di Giussano (which was following Da Barbiano in line) received the order, and while Di Giussano saw the flagship reverse course and imitated her (but remained misaligned), Cigno did not noticed