These are just some of the over 100 souvenir plates sold by Tristan Da Cunha in the Post Office on the island alongside stamps, rulers, postcards, penguins, etc. Visitors to the island have now photographed nearly all the 60 or so vehicles registered and in use on the island and none of them have ever carried plates like these. The vast majority of vehicles have hand painted numbers applied directly onto the vehicle and do not have actual plates. There were pressed plates when registrations started in 1969 that were made in South Africa and had numbers from T.D.C. 1 to probably T.D.C. 36 or 39.
The souvenir plates were first made in about 1990 and there are 3 batches. The first batch was single line with TRISTAN DA CUNHA above SOUTH ATLANTIC at the bottom with numbers from TDC 1 to probably about TDC 75, the second batch are motorcycle plates and are similar with numbers from about 175 upwards and the third batch are single line with TRISTAN DA CUNHA SOUTH ATLANTIC at the bottom with numbers from about TDC 124 to TDC 175. They are made of perspex (plexiglass), there is one plate of each number and they are sold in the Post Office for 10GBP (16USD) each. The first plates in this photo are from Olav Brekke who visited the island in 2006 and took photos of the Post Office window and the stores inside as well as most of the vehicles with registrations.
For photos of plates actually in use on vehicles, see Olav’s excellent website (Olavsplates) and his TDC pages at http://www.olavsplates.com/tristan_da_cunha_abroad.html
Remember, these are souvenirs of a type never actually used and the original cost was 16USD + postage