The 2p and 2.5p stamps.
The 2p and 2.5p stamps were first introduced in 1971 and they are available as standard definitive and Christmas themed versions. Mostly they come with lick and stick gum but the 2p green was issued with self-adhesive in the mid 2000's but we hardly ever see them.
According to the Royal Mail you still can combine two 2.5p stamps to make 5p but we never sell them as such.
Both the the 2p and 2.5p are reasonably easy to obtain from sheets and early booklets which makes them ideal for combining with other stamps to make larger values. However, most customers buy them in quantities of 100 or 200 at a time so they do go in and out of stock fast.
When we receive your order the stamps are picked at random from our stock box so you will normally receive an nice mixture of different designs and formats.