River Thames Thames Estuary), the river is subject to tidal activity from the North Sea. Before the lock was installed, the river was tidal as far as Staines, about upstream. London, capital of Roman Britain, was established on two hills, now known as Cornhill and Ludgate Hill. These provided a firm base for a trading centre at the lowest possible point on the Thames. A river crossing was built at the site of London Bridge. London Bridge is now used as the basis for published tide tables giving the times of high tide. High tide reaches Putney about 30 minutes later than
Queen Elizabeth II Silver Jubilee Medal of a diameter silver disc with, on the obverse, the words "ELIZABETH II DEI GRA. REGINA FID. DEF." (Latin abbreviation for "Elizabeth II, by the Grace of God, Queen, Defender of the Faith") surrounding an effigy of Queen Elizabeth II, symbolising her role as fount of honour. On the reverse is a crown atop a wreath that contains the words "THE 25th YEAR OF THE REIGN OF QUEEN ELIZABETH II 6 February 1977" in six lines. The Canadian version was identical, except that the medal was slightly thicker, the crown on the Queen's effigy was more upright, and the reverse