we know it is not a prototype based on what George found out.
it appears aluminium nacelles were used in the earliest batch of 1959 MK2,
and by June 1960 the controls were inverted and Bakelite nacelles were iintroduced.

whoever made the engine's aluminium parts, must have made the aluminium nacelles.

George only found out that the switches were changed over in 1960, not that the early ones were aluminium, the part no's for the early cars were different, so we all assumed they may have been aluminium.

Homer has one of the first production Mk2's but his has Bakelite, so it may well still be a prototype. And I agree that it was probably the same manufacturer that made other aluminium parts for the Jags that made the one you have.

I think I am correct in my summary, but please tell me if I am not.

The smaller cut out on the one side is still unanswered, this may help in the ascertaining exactly which model it was designed for ?

I will have another look at the parts books to see what the differences in the switches were on the 1959 cars.

Tilley Jon,
the thing is that there are other aluminium nacelles known to mankind, not just the one I have. Unless they made a number of prototypes?

Which company manufactured the cam covers, air intakes, air breathers, and other aluminium dressing parts for the XK engine? I think that they would know, if they still exist, and assuming there is no "Metal Kraft". The stamped "K88" is quite legible, so that's a start.

the small cutout on the left must be for the Overdrive stalk switch which requires little travel up/down to engage the overdrive.

the man that sold it to me told me he had two and had already sold one, he asked if I was interested and the price included "bragging rights". I paid a hefty price for the nacelle, that is why I'm broke today. I'm not complaining, it wasn't misrepresented, or the wrong part, and he did say they only were fitted in the very early 1959 batch of MK2.

that is as much as I know about it.

It would not be unusual to cast several prototypes, the aluminium would most likely be a sand mold, a pattern would be made by hand, this is then used to create the sand mould and the parts are cast in that and then cleaned up.

Cleaning aluminium castings takes time so is more expensive.

Bakelite has to have a pair of molds made for each part, these go into a press, and the parts are created under pressure (compression moulding) when the parts come out, they are already shiny, just a small amount of trimming to do and the part is done. There is also not setting/cooling time as such, so production is quicker and easier except the time required to make precision molds.

This is why I think they may be prototypes produced before the switch to Bakelite, I have to say I am making some assumptions based on the process involved, and I could well be completely off base.

the beauty of this part is that there are no "towers" or "posts" to crack open like the plastic ones. The towers are solid metal and threaded or "tapped" to fit the same identical screws as used all the way to the S type. There is continuity, everything matches other than the cutouts for the switches. Since plastic ones are marked "Lucas England" , I wonder if Lucas also had the aluminium ones made.