Early Otter Switch Alloy XK120

I need 2 C168 Otter Switches.
Used on Early XK engines and possibly MKV
Does anyone know the part number of similar switches are used on any other make or model

C168ThermostatSwitch (6)|656x500

Ed Nantes is likely your best source of info.


There were 2 manufacturers of this particular thermostat that was already used from 1937 onwards as an Auxiliary Enrichment Devise for SU’s under cold start conditions.
The picture you refer to, shows the “British Thermostat Company” version. This company (also known as “Teddington”) manufactured all sorts of thermal control equipment, including e.g. the standard cooling thermostat for early Mk VII engines with numbers A2001 to A6000.
The second supplier is Otter Controls Limited of Stockport, Manchester and later Dew Pond Lane, Buxton. The Otter version is known as the “Type US 35 ⁰C”. As Otter only started in 1946 it is possible that they took over production of this particular thermostat from British Thermostat (that also stepped out of the production of bellows thermostats in those years, leaving the thermostat market initially to Smiths).
I noticed that the same “Otter” coding is used on your picture of the British Thermostat version: “Type US” followed by 35??? (hard to see).
I’ve added a picture of the (if you want “real”) Otter switch. You’ll see that the aluminium housing and electrical connections are slightly different but both versions fit.
Will be very difficult to find one, but at least your chances have been doubled now (theoretically)…


Bob K.


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Yes, it was also used on all Mark V and previous models back to 1938. Listed as Thermostat Switch on Water Manifold for Choke Control (Type U.S. 35 deg) part no. C.168
I think U.S. means unsubmerged, i.e. not water tight?
I have only one and it has no markings on the outside.

Interesting that you mention Teddington as that name is on the cast iron thermostat housing of my Mark V.