Anything that comes out from McLaren is pure, distilled engineering brilliance (and a bit of black magic)
<img src="http://media.caranddriver.com/images/14q1/562747/2014-mclaren-p1-test-review-car-and-driver-photo-580034-s-original.jpg&quot; width="500">

I'll take a small company continuing on in the traditions of the past. Do I say Caterham or Morgan though?

There's so many specialist sports cars to pick from, but I'm gonna go with the Ginetta G40R as the most hoonworthy
<img src="http://i.telegraph.co.uk/multimedia/archive/01970/ginetta-g40r_1970769c.jpg&quot; width="600">
MX5/Ford mechanicals, practical enough that you can enjoy it the rainy climate of the British Isles unlike the masochism of an Atom or Seven and 175bhp up to propel 795KG. It fills the gap left when the Lotus Exige went upmarket and V6.
<a href="https://www.youtube.com/watch?v=LiqFGZuKtXU” target=”_blank”>https://www.youtube.com/watch?v=LiqFGZuKtXU

All of the cars in the lead image were made in Britain, mainly in England, by British owned companies,( or a company), using engines and transmissions designed and made in Britain and fitted to bodies and chassis also designed and made in Britain using steel, alloys, plastics, rubber and glass made in Britain as well.
This is no longer the case.
With two and a bit exceptions.
McLaren,the only entirely British designed & made car by a British owned company, and JCB.
The Morgan 4/4, with it's Japanese made, Mazda transmission and Ford supplied, UK made 4 cylinder engine is the bit. Other Morgans have German,(BMW V8) or American,(S&S V-twin, Ford V6) and German (ZF) transmissions.Alloy for the newer Aero chassis is from Denmark.
But Morgan remains the largest British owned car company and apart from it's transmission the 4/4 is close to being solely UK owned, designed and made.
Lotus is owned by a Malaysian company and makes cars from Danish alloy extrusions, Japanese powertrains, (Toyota 4s & V6s) but they do have a very big design operation, as do the similarly overseas owned Ricardo or Cosworth design consultancies.
Caterham owned by Malaysians use British engines and Japanese transmissions in British chassis.
Ariel use Japanese engine/transmissions,(Honda) as do Ginetta,(Mazda).
Jaguar LandRover are owned by the Indian Tata group but make all of their engines in the UK apart from the Mexican-made V8 diesels. All bodies/chassis are made in Britain. Transmissions are German,(ZF). But all design is in Britain.
Aston Martin, owned by a Kuwaiti company, are designed and made in UK from Danish supplied alloy extrusions and British composites. All engines, based on Ford designs, V8 and V12 are made in Cologne, Germany and imported.
Bentley owned by the Volkswagen group make one model, the Mulsanne, using body parts pressed in the UK. The OHV alloy V8 for this is also UK made.Transmissions are German (ZF).Design is partly British.
All other Bentleys are assembled in the UK from pressings,extrusions and mechanical assemblies scourced from Germany, although assembly of the W12 engines is completed in the UK from German supplied parts.
ALL other vehicles made in the UK use this model of assembly from imported pre-manufactured parts imported from overseas.
This includes Rolls Royce,(owned by BMW, engines, transmissions and bodies from Germany), Nissan, (Japan and France), Toyota and Honda,(Japan), GM Vauxhall,( most vehicles imported complete from Germany, Belgium,Spain, Australia. Some assembly using imported pressings and motors sourced from elsewhere in the GM empire.)
Ford which had a full British subsidiary, Ford UK until 1950 no longer make ANY vehicles in Britain at all. All vehicles are imported fully built up, but many engines are still made in Britain and exported, to be re-imported in the finished vehicle.
BMW's other British subsidiary, Mini, also assembles cars in the UK, but many parts including pressings and engines are made there. Many engines are also made in the UK and exported. Occasionally some models are fully assembled overseas and imported fully built up. The design is also largely British.
The other great British brand, MG,(all that is left of the BMC/AustinRover part of Leyland) is now Chinese owned and all assembly is of parts from China. Much design is still British however and many mechanical bits are from tooling that was originally in Britain.
To some people, this may seem like a pedantic difference, but it is not.
VW Beetles are not described as Mexican cars,although they are all made there. Camaros are not described as Canadian. BMW X-series, or Hondas or Nissans or Mercedes Benzes or Volkswagens that are made in the USA from imported parts are not described as American.
And Airbus airliners are not described as French, but European, even though all final assembly is in Toulouse, France.
Assembling cars designed overseas and using all parts imported, is only assembly in the same way that Malta or New Zealand used to have car assembly, but not manufacture. And as Australia and Britain have found out, if you don't own the companies in your own country, continued manufacture of anything is not guaranteed.
The history of British manufacture of many things, including cars, is a sad one but is none-the-less a true history of management incompetence and short-sighted investment decisions from one of the largest money sources in the world, London.