Now let's see what the cockpit of the E-series is like.
Sources of today:
"D.(Luft)T.2110 C-2,C-4 bis C-7, D-0 bis D-4, E-1 bis E-4; Bf 110 Flugzeughandbuch Teil 9D; Bordfunkanlage" July 1942
"D.(Luft)T.2110 C, D und E; Bf 110 C, D und E Flugzeughandbuch Teil 8B; Einbau und Prüfung der Abwurfwaffe; Heft 1: Bf 110 E" May 1941
"Deutsche Flugzeug-Cockpits 1935-1945" from Kennrth A Merrick
"Ersatzteilliste Bf 110 C" January 1940 with updated pages (intruduction date see lower right corner of the page)
OK, let's begin with a nice cockpit drawing(first source) of an E-Series cockpit (see the heater knob top right).
Bf-110 E juli 42.jpg
This is the standard cockpit for the E-series. You can also see that instead of the electrical prop-gauges now the switches for the automated propeller pitch are installed. Good to see on the left side the fuse box with the switches for the fuel pumps.
Also some other instruments were moved.
This drawing can be taken for true, since a picture (2. source) clearly shows the switches in the same position.
Bf-110 E May 41.jpg
But now it gets tricky.
Two nice pictures of an E-1 W.Nr.4114, SJ+KB(production code), LN+FR(military code) of 1.(Z)/JG 77 build Aug.1941 and landed in Sweden on 1. Sep.1941.
Bf-110 E-1 august41.jpg
First some additional info.
The production of the E-1 ended in August '41 with W.Nr. 4116 and it was the last Bf 110 which the Messerschmitt plant in Augsburg produced(see "Messerschmitt Bf 110, Me 210, M410" from Mankau/Petrick page 324).
The last E-series A/C were build in Januar '42 and production of the F-Series started in Dec. '41.
As a side note the F- and G-Series were build at the Luther-Werke(formerly MIAG) and Gothaer Waggonfabrik which also produced the earlier Series.
My personal conclusion:
since they needed place for the outer temp. gauge (below the heater knob), they changed the position of the automatic-switches to the left, above the prop-pitch-lever.
To do so they used the spare parts for early C- and D-Series, wich were introduced to update the manual prop pitch to the automatic prop pitch system.
I can justify this conclusion, since there is no additional plate to cover the empty gauge hole to the right of the outer temp. gauge.
See spare parts for Bf 110 C (4. source).
First one is for normal C-Series with manual prop pitch. (see part-# 14)
Bf 110 C spare parts.jpg
Second one is for updated C-Series with automatic prop pitch. (see part-# 26(new box), 27(
Cover plate), 28(prop-lever) and 29(switch))
Bf 110 C LS-automatik spare parts.jpg