There's a good account of events in S F Wise's "Canadian Airmen In The First World War", pages 441 - 444. This confirms that 380 tanks were ready at 06:10 on 20 November and that between 09:00 and noon virtually no flying was possible because of the weather. By nightfall the 3rd Army had advanced 3-4 miles along a six-mile front; although losses were light, a large number of tanks had been immobilised.
The incident with the German fighters would seem to be when Camels of 3 Sqn were detailed to bomb Carnieres aerodrome but got lost in the fog. Wise says that one Camel was shot down and three others crashed into trees on the way home.
The Camel shot down was presumably the one claimed by
Josef Mai of Jasta 5 (2nd Lt G W Hall KIA); other 3 Sqn casualties were 2nd Lt W C V Higginson KIA, 2nd Lt M W B Stead POW, 2nd Lt H P Ledger KIA and 2nd Lt T J Kent POW.
On 21 November, 3 Brigade recorded 9 successful reconnaissances and four contact patrols without noting any enemy air activity. The limit of the British advance had been reached and German reinforcements began to reach Bourlon Ridge.
Things didn't improve and over the next few days Bourlon and Fontaine-Notre-Dame were captured only to be lost again when the Germans counter-attacked.
On 26 November the squadrons of 1 Brigade, which had been operating around Cambrai, returned to their normal sphere of operations.
Four days later the Germans mounted a major assault between Masnieres and Vendhuille but this petered to a halt during 2/3 December.
It seems that the bad weather prevented the Germans from observing the build up and bogged down the British advance while wishful thinking at GHQ led to air support being diverted just before the Germans counter-attacked.
Graeme