Lewes is the ancient county town of East Sussex and happens to straddle the Greenwich Meridian.
The above co-ordinates will take you to the plaques but parking in Lewes is very expensive. Don't even think about risking parking illegally, the wardens hunt in packs, even using motorcyles. Free parking is available on the outskirts of the town.
Once at the plaques, use the following clues to locate the micro cache which is located a short distance away (10 minutes walk) at :
N 50 52.abc
W 000 00.xyz
a = the second digit of the house number for "Meridian Cottage"
bc = the last two digits of the adjacent house, the one with the blue street sign on it
x = the number of characters in the name of the foundry presenting the pavement plaque
y = the number of characters on the nearby blue street name sign
z = Ex shop/betting office how many digits are in the number of the property - NB also above the A on the door to te upstairs property.
Whilst in Lewes, leave the car and take a walk into town where you will be rewarded with so much history.