It was cold and windy on the upper deck of the ferry, but the sun shone, and the tourists, mostly from eastern Europe or Spain, endeavoured to understand the dry wit of the crew member providing the commentary.
There were numerous points of interest on the route, including Tate Modern, the Shard (At 310m soon to be Europe's tallest building), Tower Bridge, the Tower of London, resplendent in the early afternoon sunshine, and the Royal Naval College at Greenwich.
 Lunch was obtained at a Vietnamese Restaurant in Greenwich. The food was nice and different and reasonably priced, but for our taste it was too salty.  
For Greenwich Observatory it was the first day of charging for entry, a situation brought about by the vast number of visitors and the expense required to make good the wear and tear.
The main purpose of the visit was to see the area where weather observations were carried out from early in the 19th century until the 1990s. The working observatory has now moved on and since 1997 the Royal Observatory Greenwich has been a UNESCO World Heritage site.
Views across London  from the top of the hill were stunning, and the trip back along the river  towards the setting sun ended in the twilight at Westminster Pier close to the Houses of Parliament.