Interestingly I have read that the
Decca phase 4 records are preferred
to the London pressings for sound quality.
When I have spoken to DECCA about this, John Dunkerly is one source,
they were adamant that London and DECCA pressings were all done in
England thus exactly the same.
In rare cases a master tape copy was used for a foreign release but in
most cases pressing stampers were sent if there was a need for a swift
I have compared the matrix numbers on many London releases with their
DECCA releases and they are the same so far after more than a few
hundred comparisons so far during some 35 years of listening and
looking and I cannot hear any difference.
The reason given for doing it this way was for keeping the quality up.
DECCA always used the original edited master tape as the source for
the Neumann cutter as they felt that the quality loss from using a
copy tape was not acceptable at all to them.