The cache is not at the published co-ordinates although it is somewhere on the OS map extract, below.
Between us we have over 70 years of teaching Ordnance Survey map skills to young people, sometimes more successfully than at others! Six-figure grid references are always a bit of sticking point for some. Can you remember how to do them? If you can you’ll find a cache for your trouble.
Six-figure grid references are written as six numbers like this: 832748. Commas, hyphens and brackets are not used so 832,748, 832-748 and (832)(278) are not formatted correctly.
Use the OS map extract below. You are looking for spot-heights, indicated by a small black dot with a number next to it. Sometimes the black dot is on a road. The blue dot at the centre of a trig point symbol is also a spot-height. The six-figure grid references refer to the dot location not the number location.
You will find the cache at: N55 04.ABC W002 15.DEF
Find the spot-height at: 831748. First number = A
Find the spot-height at: 853751. First number minus second number = B
Find the spot-height at: 856763. First number = C
Find the spot-height at: 864769. First number = D
Find the spot-height at: 832734. Second and third numbers = EF