Best all British, except cables, system you heard or can think of.

I haven't heard such a top level system. Analogue source only.
This is an easy one for me, being somewhat of an Anglophile. London Reference pickup, Helius Omega Silver Ruby arm, Townshend Audio Rock turntable, Ear-Yoshino Acute 4/Dac 4 CD/SACD player, EAR-Yoshino 912 pre-amp and 534 power amp, QUAD ESL loudspeakers.
SME 20 turntable
Sugden Masterclass Phono, Preamp and Amp
Wilson Benesch Vector speakers
Pro Ac, Aesthetic, Linn
In the past I also had:

Rega P-25
Roksan integrated
Proac Response 2

Good but not as good as the prior system I mentioned.
Sure all Audio Note UK they make everything turntables, arms, cartridges, preamps, amps, cables, speakers.
My initial thinking would start with this : Nottingham Anna Log turntable/tonearm, Naim or Chord electronics and Harbeth 40.2 speakers. Not sure about British cartridge - Best Goldring or Roxan or Audio Note perhaps. I am not sure EAR would be a good choice to drive Harbeth but I may be wrong.
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Custom built Tannoy HPD 315 loudspeakers, Tannoy 15i passive subwoofer, Garrard 401 DIY restored turntable, ESSCO modified Zu Denon 103R cartridge, oh and KEF Q-100 center channel and Q 15.2 surround speakers, and lastly, an Arcam FMJ DV 139 universal player.

This equipment is not in any

Darn it, pushed the wrong key! Meant to say this equipment is not bright, or harsh in any way. Most people criticize Brit-gear of being a bit too laid back, if anything. Not my system, however, it's just right for my liking.
DNM very good British wires. I use them everywhere.
Bass for the Quads I left out because that HAS to be American---the GR Research/Rythmik Direct Servo-Feedback OB/Dipole Sub is the only way to go! If it has to be British, the Gradient dipole sub will do.
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Some German and French can be bright, I think.
bdp24, why not REL subs ? Should do well with Harbeth, but maybe not with QUADs
Mapman, I don't tolerate yellow badges. Please..
inna, the GR Research/Rythmik OB/Dipole Sub is a completely different animal than are sealed and ported subs, even really good ones like REL’s. It works well with all loudspeakers, but especially dipoles. A dipole sub with a dipole speaker, see? Siegfried Linkwitz designed his dipole speakers with an integral dipole sub similar to the GR Research/Rythmik, but without the benefit of the latters servo-feedback system.
Yeah, I thought so, REL with Harbeth but GR dipole with Quad.
No-one mentioned ATC speakers yet..

Everything I've hear from the brits over the years are bright

That's strange.  Lo these many years, I've owned Celestion, B&W, ProAc and now PMC, and I'm bright-averse.  A brief detour into the world of Thiel predictably proved an utter debacle.

As per inna, I associate bright with some French, German and yes, US makers.

DCS Vivaldi stack or Chord Dave + Hugo M-scaler 
EAR 912 Preamplifier 

but I like many of the suggestions above too!
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Oops my bad.

Remove the digital source and add EAR Disc Master.
Mental, the years I was between the two sets of Tannoys I've owned were spent with B&W DM 620's (I think that was the model) and enjoyed them greatly, though there were Dynaudio Contour 5.4's in there too).

That was just before my final assault on my retirement system, which I've been enjoying for some ten years noow

B&W DM1800's with dedicated stands.  Had them in my system for years and years, longest of any.  Still got 'em, packed away...
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