W M G B (West Midlands Gas Board)

The West Midlands Gas Board was formed by the Gas Act of 1948. From their use of commercial overprints on SG 488, we can infer that they started using overprinted stamps on receipts soon after being established.









There are two main patterns:

• The W M/G B pattern is a sans-serif font that is known in two font sizes:
• The 2.8mm pattern is known on SG 488, 506, 506a, 518, 518a, 543, 543a, 543b, 543bd
  573, 573a, 579, 613, 613a, 726, 727, and 736.
• The 2.0mm pattern is known on SG 573a, 613ab, and 727.

• The W. M./G. B. pattern has a typewritten appearance and also is known in two font sizes: 
• The 2.5mm pattern is known on SG 506, 518, 543, 543b, and 573.
• The 2.2mm pattern is known on SG 488, 506, 543, and 543b. 

It is very difficult to distinguish between the 2.5mm and 2.2mm patterns by font size alone, but the letters in the 2.5mm pattern are spaced 2.5mm horizontally while those in the 2.2mm pattern are 4.25mm apart.

by Michael Behm

References
http://www.ibredguy.co.uk/main.php?g2_itemId=20863
http://en.wikipedia.org/wiki/Area_gas_boards