With a lesser part of the gargantuan Chartwell collection going under the hammer at the moment and another (Great Britain King Edward VII Essays, Proofs & Issued Stamps) offered in December, we felt it was a good time for a look back.

Spink's sale of the British Empire and Great Britain line-engraved Essays and Proofs was truly a once-in-a-generation event. Here were five of our favourites.

Block of 24 Penny Blacks

By May 1841, the penny black was well established and ubiquitous. Clearly some were willing to use them to their fullest extent with a block of 24 cancelled by a red Maltese cross used on a cover.

The value of the PA-QL block would have covered missive with a weight of up to 14 ounces, and it seems this cover was used to send documents discussing the Oxford and Blenheim Rail Road.

The largest known penny black multiple known to have been used, it sold for £87,840 ($137,200 by today's exchange rate).

Bermudan Postmasters Stamp

From the other side of the world hailed W.B. Perot's Bermudan Postmasters Stamps. Created in small numbers on an impromptu basis by a postmaster tired of being short changed by missing funds for postage, they are extremely rare and coveted.

A very rare example of the second issue on cover brought £128,790 ($201,200), easily trouncing the £60,000-80,000 listing.

The Missing Virgin

In 1867 the Virgin Islands created a 1 shilling value stamp with crimson frames featuring the Virgin Mary herself at the centre.

However, a rare few of these were printed with a startling error: the Virgin herself was missing - perhaps having ascended.

Gone in a flash - the missing Virgin stamp error

An example of this doubled its £50,000-60,000 estimate to bring £202,500 ($316,400).

First month stamp use

A second penny black lot dating from nearly a year earlier also enthralled bidders. This dated to May 13, 1940, the same month as the stamp was issued in the first place.

The TL position stamp has a deep shade of colour, showing double T and external guide lines, with good to large/ very large margins all round from the lower right corner of the sheet it came from.

Once owned by L.E. Meinertzhagen, it was nearly thrown away due to being tucked into the old newspaper lining of a storage box. Just as well it wasn't, though, as it is probably the finest one penny black on cover in existence.

It went past its £200,000-300,000 estimate to bring £339,390.

The Chartwell Mauritius 'Post Office' 2d stamp

Mauritius 'Post Office' Issue

Finally there was of course the Mauritius 1847 Post Office Issue. Famously the first set of stamps issued in the British Empire outside of Great Britain itself, the Mauritius Post Office stamps were created in small numbers, originally to send out ball invitations.

The design was changed soon after so that 'post paid' appeared on the stamps rather than 'post office', making the original variety extremely rare and coveted.

Spink sold an unused 2d blue as part of the Chartwell collection which is believed to be the most beautifully preserved example of its kind for a remarkable £1.08m ($1.7m).