The St Ninian's Hoard

The story the puzzle is built on

In 1958 a schoolboy helping to clear rubble from the floor of the ruined chapel on St Ninian's Isle put his trowel through the flagstones and into a shallow pit. What came out was twenty-eight pieces of Pictish silver: a hanging bowl, twelve brooches, a sword scabbard, a silver-rimmed drinking horn, and a set of what are usually described as chapes but may have been pins. The hoard is now in Edinburgh, and a replica is in the museum in Lerwick.

The puzzle assumes you have looked at the photographs of those objects before you set off. If you have not, it is still solvable — but you will spend an hour on the beach doing it instead of twenty minutes.

Reading the objects

The listing gives five descriptions of items in the hoard, each with one detail deliberately altered from the published photographs. Identify the altered detail in each, take the number indicated by that detail, and you have five digits.

The trick is that the alterations are all plausible. The hanging bowl really does have escutcheons; the question is whether it has the number the listing claims, and the only way to be sure is to have looked at the photographs, which are reproduced in the site gallery and are out of copyright.

The arithmetic

Five digits, in the order given. Treat them as a single number and divide by the number of pieces in the hoard. The remainder is your index into the list of five-digit offsets appended to the listing. That gives you the small easting and northing corrections to apply to the published coordinate.

The final is then within twenty metres of the corrected point. Do the arithmetic on paper. Two people have logged this cache from a phone screen in driving rain and both got the remainder wrong in the same way, which is a hint in itself.

The final

A micro container in the drystone wall at the landward end of the tombolo, fourth stone up from the base on the seaward face. The stone is a small one and comes out with finger pressure. Replace it so the wall face stays flush — this wall is repointed every few years by the amenity trust and a proud stone gets spotted.

Bring a pen. The container holds a rolled logbook and nothing else.

Access and terrain

• The tombolo is a sand causeway linking the island to the mainland. It is submerged at high spring tides and the crossing should not be attempted then.
• The sand is firm but the western end has soft patches that hold water. What looks like a route on the surface is often the wettest ground.
• There is no shelter on the island. Wind funnels across the tombolo and there is nowhere to sit out of it.
• The chapel ruins are a scheduled monument. Do not move any stone other than the cache stone, and do not climb on the walls.

After the find

Bigton beach on the mainland side is a good hour of walking, and the drive south to Sumburgh Head gives you seabird colonies, a lighthouse, and the best cake in Shetland at the visitor centre.