In 1984, for the centenary of the Greenwich Meridian as the Prime Meridian (longitude = 0°), the British Post Office issued a four stamp series designed by an agency, Sedley Place.
I find the serie interesting, whereas it is simple reproduction of pre-existing pictures, because of the red line. Readers are taught to localize the meridian on many scales.
More personally, the 28 pence touch me much with touristic memories:
If you travel to London, you will not hesitate to pay a 2-zone ticket, take the Docklands Light Railway, a light most-aerian metro, until the Cutty Sark station. At the exit, you will be in the World Heritage Site of Maritime Greenwich. The Cutty Sark clipper is worth the paying visit. Free is the general visit of the National Maritime Museum (on the right on the stamp, near the royal effigy).
Noon, eat on the grass under the sun, down the hill that you will climb next to visit the Observatory. Finally, you will come back with one of the Thames excursion boats. Than to this quiet transport, I discovered the Londonian residential buildings with a new look than the front door.
Four years after, I still remember every moment of this visit to Greenwich. I encourage to do it too.