Special Sub-Topic: Let's Navigate the River Thames [2] Click Here To Play: Let's Navigate the River Thames [2]

Before setting off downstream we need to find our boat. We last saw it at the limits of upstream navigation for motorized craft. Where should we look?

Lechlade. Although rising at Cricklade the Thames does not become navigable until Lechlade. From here it travels over 200 miles before reaching its estuary, east of London.

On passing through Oxford we notice the boathouses and realise that this must be the home of the University rowing team. By what name is the second string boat known?

Isis. The name is taken from the river itself. The stretch through Oxford is known as the River Isis. The second string boat also competes in a University boat race against Cambridge, whose second boat is called Goldie.

We moor for lunch in the Oxfordshire town of Abingdon. A large building is nearby which we are pleased to find is a brewery. To our dismay we find it is disused; but which brewer can claim Abingdon as it's home town?

Morland. Morland brewed ale in Abingdon for more than three centuries from the 1700s to the year 2000 at which time the new owners (Greene King) closed the site and moved production to Suffolk. Many of the towns on the Thames have association with brewers including Henley (Brakspears), Marlow (Whitbread), Reading (Courage) and Chiswick (Fullers).

Just outside of Wallingford we are buzzed by a low flying aircraft on a final landing approach to an airfield. We remember that this used to be the home of the Queen's Flight. Which airfield is nearby?

RAF Benson. RAF Benson was the home of the Queen's Flight between 1939 and 1995. The original airfield opened in 1937 and during the war was a training ground for new pilots.

On our journey downstream we pass under one of only two Toll Bridges remaining on the Thames. We recall that we passed one at Eynsham and therefore can deduce that the town on our righthand side is?

Pangbourne. The Toll Bridge joins the town of Pangbourne with the village of Whitchurch. The original bridge was erected in 1792 and was reported in an edition of the Reading Mercury as "now open for horses and foot passengers and all types of cattle". The bridge is the third on the site and has been there since 1902.

We moor up for the night in the market town of Marlow. In front of us stands a magnificent bridge which was built in 1829. What is unique about this structure?

The only suspension bridge over the non-tidal Thames. There has been a bridge in Marlow since around 1530. In 1642 the bridge was partly destroyed during the Civil War. The current suspension bridge replaced a wooden bridge further downstream which collapsed in 1828. The suspension design is by William Tierney Clark.

As our journey continues we are amazed to see funnily dressed men, in boats with huge flags attached, chasing swans along the river bank. What on earth can be going on?

Annual Swan-Upping. The purpose of swan upping is to mark all new cygnets with the same mark as their parents. The swans are herded towards the river bank, where the cob and pen have their beaks examined to ascertain ownership, and the cygnets are then similarly marked by making nicks with a sharp knife. The reason is to determine ownership of the swan. Traditionally the current Monarch owns all unmarked mute swans on the River Thames. Marked swans are owned either by the Vintners' Company or the Dyers' Company, two Livery Companies of the City of London.

Between Maidenhead and Windsor we pass the Oakley Court Hotel which has been used in several Hammer Horror Film productions. For what reason might this location have been chosen?

Bray Studios are next door. It is possible that Peter Cushing liked the hotel and that it was cheap compared to other places but there is no evidence of this. Bray Studios however are next door and were responsible for the production of many Hammer Horror films. Hammer sold the premises in November 1970 but Bray Studios continues to host television, film work and band rehearsals. There are four sound stages.

As we cruise through central London, we hold a minutes silence to commemorate the 51 lives lost, due to a collision, on 20th August 1989. What was the name of the pleasure craft that was hit by a dredger on this fateful night?

The Marchioness. The disaster occurred when the pleasure boat Marchioness sank after being run down by the dredger Bowbelle. The two boats collided near Cannon Street Bridge. There were 131 people on the Marchioness, fifty-one of them drowned.

As our journey nears its end we pass under the last bridge spanning the Thames (The QE2 Bridge) near Dartford. We clear the bridge and our navigator is heard to utter "that was the ____ th bridge we passed under since our return trip began". What number did he mention?

89. There are 60 bridges spanning the non-tidal Thames including rail, foot and road bridges. On the tidal stretch there are 29 various types of bridge. The furthest downstream is the QE2 Bridge and the nearest to the head of navigation is Ha'penny Bridge, Lechlade. There are a further 11 bridges upstream beyond the limits of navigation.