Rare stamps: the 1935 Silver Jubilee Prussian Blue stamp

The 1935 Silver Jubilee of King George V saw a major stamp issue, with 44 crown colonies and seven other countries or dependencies issuing stamps to mark the occasion.

Britain issued the following Silver Jubilee stamps on 7 May 1935

• 1/2d green
• 1d red
• 1 1/2d brown
• 2 1/2d blue

Collectors always look twice at the 2 1/2d value from this set, due to a colour variation. A small number of the stamps exist in a different shade, known as 'Prussian Blue', which are now eagerly pursued since the value of the stamp is in the thousands. 

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How the Silver Jubilee Prussian Blue was discovered

In June, 1935 the manager of a small business in North Edmonton, London ran out of 2½d stamps and sent his office boy down to the local post office to buy a dozen. The Silver Jubilee issues of George V were in widespread use at the time, having been released a month earlier, so the boy showed little interest in his purchase as he made his way back to the office.

The manager, a keen stamp collector as it happened, took one look at the stamps handed over by the lad and almost fell off his chair in surprise. Instead of the normal blue of the 2½d, he held in his palm a block that appeared to have been printed in a quite different shade, later identified as Prussian Blue.

Grabbing the boy’s arm, the manager rushed him out of the premises, through the High Street, and back to the post office where the puzzled boy pointed out the clerk who had served him. When the manager reached the head of the clerk’s queue he breathlessly enquired: 

‘How many 2½d stamps do your have?’

He watched wide-eyed as the clerk opened his book, made a speedy calculation, and replied: ‘319’.

‘I’ll take the lot,’ the manager answered, fumbling in all pockets to find £3/6/5½d.  

Four weeks later the stamps were selling at £40 each.

Official enquires into the matter at the Post Office Stores Department revealed that four 120-stamp sheets of Prussian Blues had been colour trials, accidentally perforated, then issued in error, three sheets going to the sub-office in North Edmonton; the other going to an unrecorded office.

Only 41 had been sold over the counter in North Edmonton before the office manager bought the rest.

The unmounted mint catalogue value of a single Prussian Blue is £16,000; £13,000 used.

Incidentally, that fourth sheet was never found.

Theories on the Prussian Blue stamp rarity

For many years it was thought that the Prussian shade was the result of colour trial sheets mistakenly being perforated and issued as normal with the regular issue, but this was disproved when the stamp was measured and it was found that the issued stamp was fractionally smaller than those having come from the proof sheets.

Auctioneer Colin Such said: 'I have measured the Simpson Prussian myself and can confirm that this is the case; it is the same size as all the other 2½d examples.'

From correspondence between the Post Office Stores Department and the Controller of Stamps at Somerset House, in November 1935, it is clear that Harrisons printed a large quantity of sheets in error, in Prussian blue and these were destroyed with the exception of six sheets sent to Post Office Stores for inspection.

The Superintendent Warehouseman was asked to destroy the six sheets after a block of four was retained for reference. However, a further mistake was made and only two were destroyed, three sheets being sent to Edmonton and one to a post office elsewhere.

There is one puzzling aspect of the issue that all three panes delivered to the Edmonton post office appear not to have been guillotined between the two panes of 120 stamps printed side by side.

The postmaster had to separate two of the panes down the first row of vertical perforations of the right-hand pane, resulting in the left pane bearing control and cylinder numbers in both the left and right margins. This lack of guillotining seems only to have affected the Prussian blues.

Why was this the case?

Colin Such's explanation is that the six panes of Prussians sent to the Post Office Stores by Harrisons were left un-guillotined because they realised that they were not intended for circulation.

The overworked warehouseman failed to register not only the colour difference but also the fact that the sheets had to be separated manually. Perhaps we owe a debt of gratitude to the busy warehouseman, as he has provided us with what has become the most iconic error of colour in GB philately.