Δ  The Australian Auction House, Downies, offering for auction Specimen I, with Lot marked number 2054, outlined in red. [1]

The first specimen, is possible one of the top graded of any of the 6 known examples. Encapsulated by the company PCGS and certified as Proof 63. One the the last three pieces offered to the public within last five years. The coin now resides in a collection under private ownership.

Δ  The Spink & Sons, Ltd. Auction House, offering for auction Specimen II from The Jerrick Remick collection of coins of the British colonies & England., Lot marked number 1015, outlined in red. [2]

One of the two last pieces offered to the public within last five years in the numismatic market. The coin together with Specimens III & IV now resides in a great collection under private ownership, however I don't have photos, nor provenace details about them.

Since Mr. Remick starting collecting in the 1940's, the specimen in his collection have not been on the market for up to 60 years, explaining why today we know of a few.

Δ  This coin, Specimen V, is carefully guarded within the collection of the Mint's Museum, perhaps the only know 1870 specimen in public hands, today resides in the Mint's premises at Llantrisant, whose present structure was built in 1968. [3]

Δ  The circulated coin, Specimen VI, sold by Heritage Auction Galleries of Dallas, Texas, U.S.A., was offered through its 2012 January World &  Ancient Coins Non-Floor Session  #3017, Lot 28528. [4]

One of the three last pieces offered to the public within last five years in the numismatic market. The coin was encapsulated by NGC and graded EF-45 since it circulated! Now resides apparently in a collection under private ownership, however I don't have any provenace details about it.

Δ  Britain's 1870 Official prepaid Post Card with a printed stamp. From 1870—1894 only official pre-paid postcards could be sent in the post. At half the standard postal rate, the Post Card was immediately popular, and 675,000 were sold on the first day of issue. [5]

It is a very interesting piece whose true story may be more elusive than the coin itself. The privately commissioned coin hypothesis is probably one of the two explanations for its production, because there was no good reason to have a 1½ pence struck in 1870. There was nothing it could do in commerce because the denomination last year of regular production was 1862. 

However, since on May 26th, 1870, the British Postmaster-General recommended the production of "Correspondence Cards" and on 1st October 1870, the first official postcards in Britain were issued by the Post Office, perhaps it was proposed to answer the need for a small-denomination-easy-to-handle coin, as result of the change in postage rates for the 2 ounces efective in that year, and the introduction of a red color postal stamp of that denomination at the same time.

Perhaps pursuing the same purpose of the colonial 1/2 Farthing and Groat , who managed to be legal tender in England, but this attempt was apparently rejected by the Royal Treasury.