WSC-5362: Alexander III Short Cross Hammered Silver “Phase E” Penny. Transitional type, class 1a, 1249 – 1250. Voided short cross and stars, beardless “youthful” bust right. Read here for further information. This is one of the rarest of all Scottish pennies with only the Malcolm IV issues, the DAVIT.REX “Henry 1st” B.M.C. XV penny and the David 1^st Bishop of Carlisle penny being rarer. From the collection of a deceased Scottish collector. £3,850

The National Museum (Edinburgh) holds a single example of a phase E penny (Catalogue of Scottish Coins in the National Museum Edinburgh by Adam Richardson)). They classify it as: 
"Alexander II, without name of mint, beardless head, partly filleted, with sceptre to right. Obv: +ALEXANDER REX, Rev: +WILLAM:IOhAN.ON" 
They give a reference to Burns, Fig 75B. Their coin is 19.5 grains. It is illustrated and is certainly not a die pair. 
 
The Sylloge of Coins of the British Isles # 35 (Scottish Coins in the Ashmolean Museum, Oxford & the Hunterian Museum, Glasgow) have a single example of a phase e penny. They classify it as: 
"Alexander III, Transitional Coinage, short cross coinage, Glasgow # 90. 19.3 grains, 270 degree die axis, bust right. 
+ALEXANDER R REX and +ROBERT.ON.GLA"
The illustration shows a poorly struck coin which is not a die pair. 
 
Coinage of Medieval Scotland, 1100 - 1600, The Second Oxford Symposium on Coinage and Monetary History, edited by D.M.Metcalf, British Archaeological Reports 45, 1977: Ian Stewart's paper, "The Volume of Early Scottish Coinage" lists five phases of Short Cross coinage in Scotland, William through to Alexander III; phases a-e. For phase e, Stewart states, "...a tiny issue from Berwick, with an unbearded face and so presumably of Alexander III (1149 - 1186) before the introduction of the Long Cross type in 1250."
 
Stewart goes on to estimate the issues of all phases based on coins extant and number of dies therein. Interestingly he estimates that a coin die had an average output of 20-25,000 coins. He states: 
 
Phase a coinage is scarce ... 35-40 obverse dies were used resulting in a probable output of £3-4,000 face value.
 
Phase b coinage are the most plentiful. The obverse dies used is unlikely to have exceeded 75. The appearance of the 
coinage of phase b suggests a heavy die-output (maybe 40,000 coins per die) resulting in an issue of £12,000 face.
 
Phase c coins are from 8 dies and Stewart estimates an issue of £1,000 face.
 
Phase d coins are very rare. Stewart checked 33 specimans and found 13 obverse dies. He suggests more coins are to be 
found (hoards) and estimates an issue of between £1,500 and £3,000 face.
 
Phase e coins: Quote: "Although several Berwick dies are known of phase e, with the head of Alexander III, all the short cross coins struck from them are individually unique, and they were apparently superseded before being much used. It is therefore impossible to estimate the size of the issue, but the extreme rarity of the coins suggests a few hundred pounds face at most."
 
So a tiny issue with most coins never making it to circulation as the new long cross coinage was introduced within a 
year of phase e starting.