I have 2 bikes with those aluminum sleeves in the bottom bracket.
Both of them are Carltons.
One is a 1950 Carlton Flyer (stupidly, I removed the sleeve thinking it was not original, but also because I will be fitting Phil Wood retaining rings to the Chater-Lea oversized BB Shell.) The other is a 1967 Raleigh/Carlton Competition. It left the sleeve within the bottom bracket shell.
The Flyer is in original paint (says 'FLYER' on seat tube), so i'm pretty certain it's a Carlton. The Competition came with a Raleigh Anniversary badge, Davis fork Crown, and a Carlton trademark early rear centerpull cable-stop (not the semicircular tubular type, rather, a mid-1960's flat steel type that holds a normal brake barrel adjuster.) All these features match other Competitions in original paint on ebay.
So I'm pretty certain that in both cases these are Carlton frames.
The silver aluminum sleeve in the bottom brackets of my Carltons have a seemingly random series of triangles cut out from the sides, and do not easily slide out of the bottom bracket. Surprisingly, i think it a tube - there was no seam in the aluminum sleeve.
If yours matches this description then it may be a Carlton frame.
Your badly munged-up Brampton Alatet headset was used very commonly by Carlton. Your twin-crown front fork is probably worth as much as everything else on that bicycle. Your front fork is fantastic, I have never seen one of these on a carlton, so that's a small bit of evidence that it MAY NOT be a carlton, or the fork may be a replacement.
We need more pictures to make a better identification - rear brake bridge, showing attachment to stays - front and rear dropouts ~ brazing style. - bottom bracket cable-routing, if any - downtube shifter stop, if any - bottom bracket cutout, if any.
- Don Gillies
San Diego, CA, USA