William Henry James Alexander was born at Gravesend in 1858.  He was apprenticed as a waterman and moved to Wapping, close to the Pool of London, where he remained for most of his life.  He became a wharfinger and starting from quite a junior position rose to manage the business owned by Messrs. Hall and Gregory involved in the storage of sugar products.  When the opportunity arose he took over the provision of lighterage services to the business.  He eventually came to control both the St. John’s Wharf and the King Henry Wharf.  A major customer was the Tate refinery (Tate & Lyle after 1921) at the time the biggest sugar refiner in the world.
Alexander’s first tug was the Little England of 1883/1884.  She was not a great success and was replaced by more suitable vessels, made to special order whenever possible.  By 1899 Alexander had tugs that could be used to handle lighters or ships and the Sunrise, for example, did a fair amount of downstream work in her early days under Captain Mee before reverting to work with the big sugar barges.  Her consort, the Sunshine, also worked away, at Queenstown and elsewhere, and had T A Frost appointed as “sea-captain” in 1901.  Alexander decided to aim specifically at the ship towage market and in a remarkably clear-sighted act ordered the Sun II of 1909: at 200 tons and 750 ihp, the largest and most powerful tug on the river.  This was the first step in a building programme that continued during the First World War, culminating in 1925 when the Sun XV, the eleventh in this class of large tugs, was delivered.  A number of high calibre shipping clients were acquired, including Cunard, when they came to London in 1922.  The firm also handled RMS steamers and grain ships and had the contract to move grain elevators around the docks. The building programme must have been expensive.  I do not know if any of the shipping clients helped financially.
Alexander felt the need for a presence at Gravesend, so, just as William Watkins had used the waterman and agent Isaac Coy and his sons as his representatives at Gravesend operating from the Amsterdam and later the Three Daws, Alexander used the waterman and Lloyd’s agent Percy Bowen.  The Bowen family supplied boats and watermen for mooring and ran the London Steam Tug boat Bulldog in the 1880’s and 1890’s.  The retired Trinity House pilot Spencer Bowen was still living in Milton Place, Gravesend, in 1950.  One of the Bowen girls married Arthur Alexander: another married into the Lukes family.
The Sun II did a fair amount of sea work when new under captains Mcneale and Thornton and at the time carried a young George Cawsey as a certified mate to help with navigation, the tug going as far as Madeira on towing trips.  George Cawsey later became a tug master himself and was to captain the Sun II.  The Sun VII of 1917 towed a number of the old wooden wall navy ships off to scrap after World War One and also brought all the firm’s “Lunar” lighters down from the builders at Hull.  The Sun tugs were fortunate in the way of salvage, mainly on the Thames.  The Sun II and Sun III were among the fourteen tugs to share in the £115,832 paid out on the Salatis (1909/1910), but most memorable was the saving of the burning tanker Elkhound, towed away from the oil berth in 1930 by Sun IV and Sun XII captained by W H J Alexander’s sons Charles and Sidney.
Alexander had six sons.  William Proctor and George Frederick helped their father with the lighterage side of things and became managing directors of the business as a whole after his death, while Charles and James are perhaps the two best remembered for their later role in running the ship towage business.  I think that James also lived in Milton Place at one time.
When Alexander died in 1929 he owned considerable wharfage and warehouse facilities and a substantial fleet of ship-handling tugs, lighterage tugs and lighters.  Much of the lighterage business was run in conjunction with Tate & Lyle and Tilbury Dredging.  In 1938 Tate & Lyle decided to buy out their associates, so the relevant plant was transferred to Silvertown Services, leaving Alexander’s and Tilbury Dredging to concentrate on their other activities.  Tilbury Dredging has stated that it did not have time to carry out any re-investment before the intervention of World War Two.
The Sun tugs played their part in both World Wars and this has been recorded elsewhere.
The hectic activity on the river post 1945 was a welcome change to pre-war days and the firm acquired two new oil-fired tugs laid down under the Ministry of War Transport programme to replace war losses.  These were slightly larger and more powerful than the  Sun II type.  The next step was to move into diesels, starting in 1951 with the Sun XVIII, a tug of just 103 tons, but as powerful as the Sun II.  The Sun XIX of 1956 was the first tug with the distinctive modern look and eight more tugs followed.  The last was the Sun XXVII of 1968.  George Scott was acting as manager during this period.  Alexander’s merged with the Ship Towage group in 1969 to form London Tugs and a period of consolidation and improvement followed, with several tugs being fitted with tow-master devices to increase bollard pull.  Much larger mergers were taking place around Britain and in 1974/5 the business of London Tugs was taken over by Alexandra and a new chapter of towage on the Thames began. 
All the above kindly supplied by Kevin Haydon 
11-10-2013 - SUN XV was at Gravesend from new until mid sixties. My dad Bill Toms was crew member for 30 years and Joe Lukes was skipper of her at Gravesend. He was skipper of SUN X1 at Woolwich.
Kind Regards - Keith Toms.