Air battle of 23 November 1940 over Kent

[Ludovico Slongo]

In Christer Bergström’s excellent book The Battle of Britain, an Epic Conflict Revisited, on page 269, there is a verbatim quotation from a recollection by Hans-Ekkehard Bob, a veteran pilot of III./JG 54, referring to a combat between Italian CR.42 fighters and Spitfires:
“I remember once when some Italian biplane were attacked by Spitfires. I was so amazed that I forgot to intervene; for the next few minutes I witnessed a most amazing air show (…)”.
By a process of elimination, this quotation can only refer to the air combat that took place in the early afternoon of 23 November 1940, when Spitfires of No. 603 Squadron indeed engaged CR.42s of the Italian 18° Gruppo over south-eastern Kent, off the coast near Folkestone.
Although several Italian pilots who took part in that engagement reported that a Luftwaffe fighter escort was assigned to provide high cover above them, and some of them also recalled seeing the condensation trails produced by these fighters, I have so far been unable to determine which Luftwaffe unit was actually operating over southern Kent on the afternoon of 23 November 1940.
Rather than clarifying the matter, Hans-Ekkehard Bob’s recollection raises further doubts, since a number of authoritative secondary sources suggest that his unit was already engaged in air defence duties over the Netherlands on that date, and therefore should not have been present in the area where the German pilot stated he was flying.
Among the experts who frequent this forum, is there anyone who can identify which German fighter unit was operating on Noveber the 23rd 1940, in that area (over Folkstone) at that time (around 14:30 Italian time, GMT+2)? And, if such a unit can be identified, is there any plausible explanation as to how Hans-Ekkehard Bob might have been flying with it?