To find the cache, start at the listed co-ordinates and follow the clues to discover five numbers: A, B, C D and E.
The listed co-ordinates are the centre of Baker Street. When you're there, you'll see a building where Dr Watson might work. Reverse the street number of this listed Victorian building to obtain B.
Walk towards the setting sun, counting the number of policemen lying down on the job until you reach the end of the street. This number gives you E.
Were you paying attention on your little walk? You just passed a building that Holmes would thoroughly disapprove of, but not his creator, who probably would have been more than willing to drop by one evening. The street number of this building will give you A, C and D if your maths is up to it.
A to the power 3 gives the first digit of the number, D to the power 2 gives the whole number, and C to the power 1 gives the second digit.
The cache is located at the following co-ordinates
N 51° 27.AB W 000° 59.CDE
The final co-ordinates should not be too far away from where you are now.
Please be careful when replacing the cache to put it back exactly where you found it. It is intentionally hidden in plain sight.