Just below Limehouse Hole, and at a little distance from the eastern shore, lies Limehouse Rock, on which are only four feet. Opposite the Victualling Office at Deptford, on the Isle of Dogs side, a shoal begins, and extends about one-fourth over the River, which makes the channel very narrow between it and the ships at the Red House. You will avoid it by keeping Deptford Spire just open to the westward of the Clock House
in the Royal Dock Yard.
GREENWICH REACH lies winding in a circular direction from S.S.E. to E.N.E. At Deptford Creek a shoal begins and runs down almost to the west end of Greenwich Town; it nearly dries at low water: outside this shoal are 13 or 14 feet. The Clock House on with the two trees in Deptford Yard just clears it……..
……..On the north shore, off Millington’s or Anchor Wharf, and close in shore, is another shoal, which will be avoided going down, by keeping the Storehouse Clock in Deptford Yard open to the southward of the Isle of Dogs Ferry House, until Blackwell Reach comes open.
Excerpt from The New British Channel Pilot 1839.
The clock tower of 1712-20 replaces an earlier tower of the seventeenth century. Imagine Greenwich losing the turret from its seventeenth century Flamstead House, another maritime structure employed to set ships' clocks in the Thames, or another building contemporaneous with the early Eighteenth century Deptford Dockyard clock tower, the Royal Naval College losing its domes.