are "LONDON" pressings made in the UK, inferior to the Decca pressings

@amg56: thanks, my pleasure!

BTW: a scan of this test pressing slip of the Borodin can be found on Michael Fremer's (analogcorner) and Arthur Salvatore's (high-endaudio) websites. This last guy is on some sort of crusade against  what he calls 'first pressing fundamentalists' and offers a conspiracy theory of greed that would be behind the propagation of the SXL superiority. Big words for something as unimportant as vinyl records (for 'normal' people, not for us of course!), but it's still an enjoyable read.

Hello edgewear,
If your first post is indicative of what you have to contribute, future posts will be much anticipated and appreciated. 
Charles 

Some general info for better understanding

Decca SXL made the very best recordings (from the Team, Hardware and from general understanding...Mercury is a different chapter) from the music repertoire we can listen today.
Decca was extremely careful not to get bad customer feedback (distortion, overdrive, don’t forget, those were different times from cartridge design- round diamond tip - ...) and SXL was a sale on commission!! Unsold records came back to Decca and were melted.
That is the reason why they are so expensive today. Simply limited Quantity.
Sound is - or was - first rate. I think, a Benchmark which was never surpassed for their Titles.
Those Stereo SXL were very expensive in the early 50’s and it was pure luxury to get those after the war, the Economy was still down.
In USA there was a similar economic situation but fixed pricing was cancelled around 1960.
London CS was created from Decca because Decca couldn’t use their own name in USA.
(There was a small private label which was named Decca). To avoid any problems, Decca decided right from the Start to create for USA a new Name, London.
Now for the "Sound"

For both Labels they used the same Mastertape.
But the main difference was - or is - the Peak of the cutting process. Decca thought, the US listener expects a different kind of sound, the result was a ~ +2dB Peak in the cutting.
This means, a distortion in the headroom was accepted.
But this is rare, those Decca Cutters were real artists, unsurpassed. But they can sound a bit different based on that (depends on your ears and quality of playback chain).
Next difference, Decca thought that USA wants something "Physical", means, thicker LP’s.
For Londons they used 20gr to 40gr. more vinyl. This varied a lot 1958/1959 and became Standard from 1962 (∼ 205gr). When you compare such records (SXL / London) you should use a Arm with VTA adjustment. This is mandatory.
It is a very interesting chapter for a curious audiophile, because we have different diamond cuts in our carts and that will make a huge difference when we talk or rate such records.
Also, not every SKL was available as a London CS and reverse. And of course, completely different Prints onto the Box.
Decca was also very open for information transfer, they had a good Management and later a Partnership with RCA (Living Stereo) to do their European recordings. RCA was happy because those sessions were way cheaper than in USA (affiliated unions).
A class on its own again...but this is also a different chapter.

Syntax,
Interesting points that in summary do not dispute or contradict the gist of what edgewear has posted.
Charles 

@syntax
"London CS was created from Decca because Decca couldn’t use their own name in USA.
(There was a small private label which was named Decca). To avoid any problems, Decca decided right from the Start to create for USA a new Name, London."

From Wikipedia, fountain of all knowledge:

Decca Records is a British record label established in 1929 by Edward Lewis. Its U.S. label was established in late 1934 by Lewis, along with American Decca's first president Jack Kapp and later American Decca president Milton Rackmil. In 1937, anticipating Nazi aggression leading to World War II, Lewis sold American Decca and the link between the UK and U.S. Decca labels was broken for several decades.[1] The British label was renowned for its development of recording methods, while the American company developed the concept of cast albums in the musical genre. Both wings are now part of the Universal Music Group, which is owned by Vivendi, a media conglomerate headquartered in Paris, France. The US Decca label was the foundation company that evolved into UMG.