The sixth in the series of British Pillar Boxes was issued in October 1972 (2/8/72) and illustrated the Mellor design, 1968 — 5,626,240 printed and was also used for the December 1972 issue (30/10/72) — 3,515,380 printed.

British Pillar Boxes No. 6.
The cover drawing shows the latest type of pillar box. Designed by David Mellor the first went into service near St Paul's Cathedral in 1968. The red box is rectangular in shape and bears the Royal Cipher and Crown. Unlike its predecessors it is made up of replaceable panels, but the greatest improvement on other boxes is its internal clearance mechanism.

The seventh in the series illustrated the King Edward VIII type of 1936 and was used for the February 1973 issue (5/1/73) — 4,098,840 printed and the April 1973 issue (2/4/73) — 987,690 printed.

NOTE — Originally there were to be only six designs in the series but a late decision was made to extend the series.

British Pillar Boxes No. 7.
The cover drawing shows a pillar box made in 1936 during the brief reign of Edward VIII which still bears his cipher. 161 pillar boxes were cast with the Edward VIII cipher but later, to avoid embarrassment upon the accession of George VI, the doors of many were replaced by those bearing the cipher of the new monarch.

The eighth illustrated the Standard Queen Elizabeth II type and was used for the June 1973 issue (18/4/73) — 4,098,270 printed and the August 1973 issue (4/7/73) — 2,020,200 printed.

British Pillar Boxes No. 8.
The cover drawing depicts a pillar box of the present reign, bearing the royal cypher of Queen Elizabeth II. In Scotland letter boxes bear a representation of the Scottish Crown instead of the usual cypher of Elizabeth II and the Crown of St. Edward. The first pillar box of the present reign was erected in November 1952 in Whitehall.

Illustration number nine was of the Double Aperture type of 1973. This illustration was used for three issues — October 1973, (16/8/73) — 4,943,530 printed, December 1973, (12/11/73) — 101,980 printed and February 1974,(17/12/73) — 2,959,610 printed.

British Pillar Boxes No. 9.
The cover drawing shows a double aperture pillar box presently in use in London and in some other large cities. It is rectangular in shape and is made up of steel panels mounted on a cast iron frame. The main advantage of this type of box is that it is quicker and easier for the postman to empty. External features of the box were designed by David Mellor.

Number 10, the last in the series illustrated a Philatelic Posting Box of 1974 and was used on the April 1974 issue,(22/2/74) — 3,415,930 printed and the June 1974 issue, (23/4/74) — 4,226,130 printed.
On the June edition the gum was changed from PVA to PVAD.

British Pillar Boxes No. 10.
The cover drawing shows a philatelic posting box which was introduced in some Post Offices in February 1974. It is meant to provide facilities for posting mail which has a philatelic significance. Designed by Douglas Scott Associates, it is manufactured in two parts from polyester resin/glass fibre and is coloured throughout, the upper in red, the lower in white.