Decca label designs

Below are all known UK label designs for Decca catalogue sequences that included classical repertoire between the end of WW2 and the end of 1959. All sequences are mono, unless stated. All sequences concentrated singly on classical music, unless stated.

78s

Hopefully, there will be an image coming soon for the 10" 78, M (AM for automatic couplings) sequence Red Label series (unless, as strongly suspected, it is exactly the same as the 12" K label below) and also for the 12" 78, X (AX) Gold Label series.
Note that by adding an "A" at the start of a prefix denoted an automatically coupled record (i.e. part of an album set for use on record autochangers), so the AM sequence label design is the same as that of the M sequence (AX for X and AK for K ditto).
The Red Label series was a popular music sequence including popular classics.

Red Label series 12" (K prefix; see notes above)

LPs

The Red label design was also used on popular music sequences, as was the Blue label stereo label design. With stereo labels, the second letter of the prefix matches those of the Gold and Red mono label designs. The first Decca stereo LP label designs are now known in collecting circles as "Wide Band 1"(WB1); there were slight changes in wording placement in the early 1960s.
After the Medium Play format was discontinued (see section below), the LW sequence was continued for 10" LPs - note that the MP logo has been replaced by the LP logo.

Gold Label series 12" (LXT prefix; 10" LX prefix label is identical)

Red Label series 12" (LK prefix; 10" LM prefix label is identical)

Black stereo label (SXL 12" series)

Blue stereo label (SKL 12" series)

Black label 10" (LW prefix; see notes above)

Blue label Immortal Classics series 10" (BR prefix)

10" MPs (Medium Play)

A confusing format, meant for pieces that were too short to warrant a 10" LP but too long for 7" SP (single). It should have died a death as soon as the 7" EP format was issued, but Decca preferred to use the EP for popular music and the MP for classical for a while, prior to switching the 10" MP format into another 10" LP series (see above). The fact that many MPs were longer overall than many 10" LPs was merely a curiosity. They also took the same amount of vinyl to manufacture as for a 10" LP but with far less monetary contribution to Decca.

Initial Black label with gold text 10" (LW prefix)

Later Black label with silver text 10" (LW prefix)

7" SPs (Short Play)

The SP format, now better known as 'singles', was confusingly originally viewed as a Long Play format (i.e. stacked on an autochanger record player, as per earlier 78 'albums'). Decca's first singles came out a while after those from the EMI group of companies, by which time the original RCA Victor large spindle hole format had been superseded by the normal 78 and LP spindle size, though with push-out centres for playing on old large spindle 45 rpm-only record players.
Apart from a series of Kathleen Ferrier releases in the Classical Cameo series, Decca used the SP format exclusively for popular music.

Red label Classical Cameo series (71xxx prefix; original ffrr logo and 'straight' Decca text)

Red label Classical Cameo series (71xxx prefix; later ffrr logo and curved Decca text)

EPs

The DFE sequence was for popular music including popular classics - an image will be added as soon as a suitable example appears. The stereo STO Blue label sequence was also a popular music sequence, and an example is only included because the stereo demonstration record shown included a piece from the very hard-to-find España stereo LP.

Green label series (CEP prefix)

Green label stereo series (SEC prefix)

Blue label stereo series (STO prefix)