The cache is not at the stated coordinates.
Letterbox Hybrids are a special type of cache which aim to replicate the original Letterboxes placed on Dartmoor. The location of the Dartmoor Letterboxes is sometimes defined by reference to different features on the landscape - the location of this Letterbox Hybrid is defined by OS symbols on the Landranger series of maps.
You can solve the puzzle using OS Landranger Map 188 or you can solve it online, using Streetmap. Note that the scale on-line must be set to 1:50,000 (zoom level 4) for you to see the correct map symbols. Start at the Hop Farm, grid TQ6747 on the paper map.
To solve the puzzle simply follow the list of instructions, moving from 1km square to 1km square in the direction indicated until you find the appropriate map symbol. From the start point move East examining each 1km square until you find one that contains a Bridleway. Then, from the centre of that 1km square move South East until you find a Railway Line. Follow through the whole list, picking up the values along the way.
For clarity, it is the position of the symbol that defines the square, in one or two cases the symbol may have a little line pointing outside the square or may break a boundary, the location needed is the square containing the bulk of the symbol. In all moves you will travel at least one square, and the longest move is less than 10 squares. Some of the symbols are difficult to see – just keep looking.
| E to |
Bridleway |
|
| SE to |
Railway Line |
|
| E to |
Station |
No of B road entering top right - ABCD |
| S to |
District Boundary |
|
| W to |
Camp/Caravan Site |
|
| SW to |
National Cycle Route |
No of National Cycle Route - EF |
| NW to |
Post Office |
|
| S to |
Heliport |
|
| NW to |
Spot Height 142 |
|
| N to |
Electricity Transmission Line |
|
| W to |
Parking |
|
| NW to |
Information Centre |
|
| N to |
National Trust Property |
Property name, letters in two words - G, H |
| NE to |
Road with gradient 14%-20% |
|
| N to |
Church with Tower |
|
| NE to |
Motorway |
Number of motorway - IJ |
| E to |
Club House |
|
| S to |
Church w/o Tower or Spire |
|
| E to |
Church with Spire |
|
| NE to |
Milestone |
|
| E to |
Milepost |
|
| S to |
Railway Cutting |
|
| SW to |
Public House |
|
| SE to |
Picnic Site |
Spot Height in Square - KL |
| SW to |
Level Crossing |
|
| SE to |
National Trail |
|
| N to |
Nature Reserve |
|
| SW to |
Mast |
Selected Tourist Site, letters in two words - M, N |
The cache is located in the final square at:
N51 (D-F) (F/H) . (E+L) (D+B) (L+N) E0 (F/H) (A+K) . (H-M) (F+E) (J-I)
You can check your answer at 
I have tested the route on both a paper map of 2010 vintage, and using the on-line Streetmap website. Of course OS Maps get updated from time to time, so if you find you are struggling let me know where you have got to. I will check that all is still well and give you a pointer to the next symbol.
This cache is based on Mappy Monday in Poole Harbour, by deskdata (who kindly tested this route), which in turn was based on What's That On The Map 2 cache in Devon, by Maliplex & Trublatmill .
***** Congratulations to Deepdiggingmole on the FTF *****