This live 1975 Beethoven recital contains Richter accounts of the early Sonata #3, the Bagatelles Opus 126 (just #1, 4 & 6) and, the star attraction, the "Hammerklavier" (Sonata #29). This program competes directly with Richter's live Prague accounts of the same works (in a deleted 15-disc Praga CD set). Here are some impressions based on listening to both performances, plus those by a few other pianists.
The Sonata #3 for BBC, to my taste, is played with a percussive severity that borders on excessive. The Prague is just a shade gentler and more to my liking (both are superb). The latter is played with the first mvt. repeat, whereas the BBC omits it. Richter was a zealot when it came to repeats, and I suspect that BBC has simply excised the repeat here to squeeze the program (which runs 77:45 as is) on to a single CD. Frankly, I feel that's a highly questionable aesthetic decision (IMG did a similar editing job on a Beethoven symphony in their volume dedicated to Furtwangler). My other favorite performances of this work are Wilhelm Kempff's small-scale pointillistic account (mono DG), the Claudio Arrau on Philips LP (particularly for the intense depth of his slow mvt.), Artur Schnabel (mine's on a Dante CD set - it is similar in its bold projection to Richter's), and the Yves Nat on EMI (an under-rated complete set in mono that has an amazing variety of subtlety and nuance).
Richter's BBC & Praga accounts of 3 Bagatelles from Op. 126 are pretty similar - all in all, I find a little more interpretive fire in the Praga. Both are among my all-time favorite readings, though I don't feel that Richter or anyone else quite matches the rich wisdom and total coherence of Schnabel's aged mono account of all six.
That brings us to the Hammerklavier, the most fiendishly-difficult Sonata to interpret ever written by Beethoven (or anyone else, for that matter). The composer's original metronome markings in the outer movements are incredibly fast, while the extraordinary Adagio - of almost Brucknerian dimensions - requires an enormous reservoir of deeply-felt emotion. I suspect that the "perfect" Hammerklavier has never been recorded and probably never will. The first of those to try plunging head-long into it at the specified fast tempo was Schnabel, and he misses almost as many notes as he hits. Two accounts that achieved rapid tempo success where Schnabel failed are both on out of print LPs: Beveridge Webster (Dover) and Charles Rosen (Epic), while Rudolph Serkin came close (Sony). But all three turned in fast and rather chilly readings of the Adagio, which Schnabel did sublimely (as did Kempff in his mono DG set). Solomon Cuttner (mine's on Odeon LP) was sure-fingered throughout his reading, but somehow his interpretation strikes me as just a little too smooth and sophisticated (others feel very differently).
So where does that leave this Richter account, performed just a week after the live one in Prague? Together, they represent the most stupendous LIVE performances in my experience. Both times, Richter adopts a moderate tempo in the first mvt., his 2nd mvt. is alive with rhythmic flexibility, and the final mvt. is almost over-powering in its torrential virtuosity. But there are differences, too. In the Prague, things come almost un-glued for just a second or two (around 8:20 into it), while no such mishap occurs in Aldeburgh. The shortcoming to both Richters for me is the slow mvt., which lacks slightly the tear-choked quality of Schnabel (the Praga comes perhaps a little closer than the BBC). And the recorded sound is quite different in Richter's two versions: BBC is more distant and slightly more clangorous, while the Prague is more close-up and personal (I prefer the latter's sound over-all).
Both of these extraordinary performances of the most challenging sonata ever written are ESSENTIAL listening. In my own personal pantheon, they join the Schnabel (Adagio only), the mono Kempff (perhaps the best Adagio after Schnabel's), the iconoclastic and hugely-dimensioned Ernst Levy (Marston), and the more intimate and smaller-scale Yves Nat. I'm sure there are other great accounts out there, but you can't go wrong with any of these.