Great Western Railway Dean Era Coaches

	C	A	E	12	C	N
C - Clerestory Roof						B - Broad Gauge Body Width - 10' 0¾"
L - Low Roof						N - Normal Body Width - 8' 0¾"
						W - Wide Body Width - 8' 6¾"
						S - Slim Body Width - 7' 6¾"
Only used if first letter is 'C'
A - Single Arc Top Roof						Optional letter
E - Elliptic Top Roof						C - Converted from Broad to Standard Gauge Body
						M - Metropolitan style body sides
A - Single Arc Main Roof						R - Restaurant, Sleeper type clerestory
E - Elliptic Main Roof						T - Transitional style body sides
					0 - no eaves panel above compartment windows
					4, 7, 9, 12 - height in inches of panel above compartment window

Roof
The first 2 or 3 letters define the roof type. The drawing below illustrates the five main types of roof style of Dean period coaches.
Eaves Panel
The number in the middle of the code relates to the height of the eaves panel and this can often be the hardest part of the code to determine when looking at an unknown photograph. The drawing below illustrates all the eaves panel variations together with the doors that they were used with. Notice that the 0, 4" & 9" were slightly shorter than the others. Also notice that there are different numbers of lines across the ventilators in the doors.
Optional Letter
T -	the Transitional body side style is where the compartment windows are taller than the door window, as shewn in the drawing above. Not requried when the optional M letter is used.
R -	the Restaurant style refers to the different clerestory roof that restaurant and sleeper coaches had. This is an addition to John's original classification.
M -	the Metropolitan body side style where the door ventilator is semi-circular. These coaches were originally built for the Metropolitan services.
C -	the Converted style denotes a coach body that has been converted to standard gauge from a broad gauge coach.
Body Width
N -	Most GWR Dean coaches were 8' 0¾" wide and had 5 vertical panels on the ends, as illustrated in the top drawing above.
S -	Prior to 1871 coaches were only 7' 6¾ wide. The code for these coaches is S. This letter is not used in John Lewis' article. I have yet to establish if the dimensions of all of these coaches were similar, especially since some were built at Worcester and Saltney.
B -	Later Broad Gauge coaches were the normal 8' 0¾" wide bodies but mounted on a broad gauge chassis, but earlier coaches were 10' 0¾" wide and had 7 vertical panels on the ends. The code letter for the later coaches is B.
C -	When the 10' 0¾" wide Broad Gauge coaches were converted to run on the standard gauge they became 8' 0¾" wide and had 5 vertical panels on the ends. The code letters for these coaches is C.
W -	From 1884 some coaches were built an extra 6" wider than the normal width. The code letter for these coaches is W. Initally the only wide coaches built were for the London Metropolitan line services. Later, other coaches where built 8' 6¾" wide, although all were bogie coaches with the exception of the odd saloon. Most wide coaches had 6 vertical panels on the coach ends, but at least the first 8 built only had 5 panels. Many of the later 8' 6¾" wide bogie coaches had psuedo corridor ends as if they might later be converted to corridor coaches.
Lewis Classification Codes is Historic Order
Not all of the possible permutations ever existed. The permutations of interest here are:
LA9S	1868 - 1870	In the late 1860s the GWR started to build it's own standard gauge coaches at Saltney, Worcester and Swindon. These coaches were 7' 6¾" wide, just like those it had been purchasing from external contractors. They were low roof coaches with an arc roof, short windows with deep eaves panels above that were about 9" deep. The doors had ventilators above a droplight and the ventilator was the same height as the eaves panel. The ends were vertical with no turnunder, yet there was a moderate 3" turnunder on the sides.
LA9N	1871 - 1884	In 1871 the first 8' 0¾" wide coaches appeared. They were in most areas very similar to the preceding LA9S coaches. The eaves panels were 9¼" tall, the body height was 7' 3" and the roof above 11' 2" above the rail. The ends had 5 vertical panels. Early coaches had flush ventilators, but soon bonnet ventilators appeared and the earlier ventilators were replaced as they went through the workshops. Around 1875, the ends got turnunders like the sides. The LA9N style was the most common of the early styles with 1560 coaches being built.
CAA9N	1876 - 1880	The first GWR built clerestory appeared in 1876. At first glace it looks as though a clerestory was placed on top on a LA9N body. Actually the main roof radius was increased to flatten the roof and give height for the clerestory. 37 coaches of this style were built.
CAA12B	1876 - 1882	Also in 1876 the first Broad Gauge clerestory coaches were built. The eaves panel was 3" taller than used on standard gauge coaches. 80 coaches were built to this style.
LA9B	1877 - 1882	In 1877 a 6 Broad Gauge passenger brake vans were built that were 10' 0¾" wide. In most ways they were similar to LA9N. Due to their width the ends had 7 panels.
CAA12N	1878 - 1885	From 1878 standard gauge clerestory coaches had 3" added to their height by increasing the eaves panels to 12¼". 156 coaches were built to this style.
CAA12W	1883/4	5 postal vans were built that were like CAA12N but 6" wider.
LA0MW	1884	In 1884 the first Metropolitan coaches appeared. They had wider bodies, but still only 5 vertical panels on the ends. The doors had semi-circular tops and the windows were rather odd in that they reached right up to the gutters and so there was no eaves panel. Only 8 coaches of this style were built.
LA12N	1884 - 1887	Also in 1884 the design of the low roof coaches caught up with the clerestories as the depth of the eaves panel was increased to 12¼". This made the bodies 3" taller than the previous designs. 73 coaches of this style were built.
LA12B	1885	Broad Gauge coaches were built at the same time with the increased eaves panel. Only 15 coaches were built to this style.
LA4TN	1885	1885 marked the beginning of a couple of years of style experimentation. About 40 coaches were built with the depth of the eaves panel reduced to 4". Everything else about the design was the same as the earlier LA12N.
LA7TN	1886	The in following year about 80 coaches were built with a 7" eaves panel.
CAA7TN	1886	Also in 1886 14 coaches clerestory coaches were built with the same sides as LA7TN.
LE7TN	1887	A further experiment ensued in 1887 when the LA7TN style recieved a three arc elliptical roof. This had the advantage that it was taller inside the coach near the sides and so the coaches felt roomier. Only 8 coaches were built to this style.
LE12N	1887	In 1887 the LA12N style also recieved a three arc elliptical roof. Only 10 coaches were built to this style.
LE7N	1887 - 1903	Eventually the design office arrived at a style that they liked in 1887. They took the LE7TN style and altered the doors so that the ventilators were the same height as the eaves panels. This style was the most common of the later non-clerestory styles with 875 coaches being built.
CAE7N	1887 - 1891	The clerestory designs received the same side and main roof styles as LE7N. However the clerestory roof still retained a single arc roof. 460 bogie coaches were built to this style.
CAE7W	1887 - 1892	Only 6 wider postal clerestories were built like CAE7N but 6" wider.
LE4MW	1887 - 1898	Also in 1887 the Metropolitan style recieved a three arc elliptical roof. As the side were 3" shorter than other coaches of the time, a 4" eaves panel was used. Despite their popularity there were only 315 of this style built.
Bay Window	1890 - 1897	6 coaches were built to this style. The coaches anticipated the yet to come CEE7W style but the doors had semi-circular tops of the Metropolitan styles, albeit a little taller. Between the doors the body width was gradually increased to 9' 0¾ over the windows at the compartment partitions. Similarly the width also increased from the floor up and the gutter down, making them a more like oriel windows, rather than bay windows. The clerestory roof appears to be the first time that the clerestory roof matched the main roof profile.
CAE12CN     LE9CN     LE12CN	1891/2	Following the end of the Broad Gauge, the coaches were converted to standard gauge by reducing the body width to 8' 0¾" wide. These were former CAA12B, LA9B and LA12B styles. However, when you look at photos of the conversions, in many cases it looks like the roof was given a single arc like this D2 or V8.
CEE7N	1892 - 1894	In 1892 the clerestory roof was altered to match the main roof profile and given a scaled down three arc roof. 569 coaches were built to this style.
CEE7W	1892 - 1904	At the same time 8' 6¾" wide versions were built. 955 coaches were built to this style.
LE7W	1892 - 1896	16 low roof bogie coaches were built 8' 6¾" wide.
CEE7RW	1896 - 1903	12 restaurant coaches were built with wider clerestories than CEE7W that flaired out at the bottom.
Royal     Clerestory	1894 - 1897	The Directors and Royal coaches looked much like CEE7W except the roof was extended beyond the coach end and the clerestory was wider.