As morddwyd says there are monthly variations in the range of the tide (Difference between high and low water - the biggest range occurs at springs and the smallest at neaps. In addition there are seasonal variations too.See Here: click here
Have you a copy of the Tide tables for your area? These will show the details. All tidal heights are measured from the mean low water Springs at Newlyn.
A period of high pressure which we are currently experiencing will have the effect of lower tides but not to the extent that Terry Brown indicated. Similarly low pressure results in higher tides and and since this is associated with storms and wind driven higher seas we are more used to that effect than lower tides. Low pressure, storms and a spring tide can and do cause flooding.
I have been observing the sluice gate levels for approx 4 years, and it's normal level (High Tide)is between 4' (48") and 4'7" (55") throughout the year. February was exceptional due to the heavy rain when it reached 4'11" (59").
Low Tide previous to March this year was never lower than 3'(36"), even in periods of prolonged dry weather.
Woolwell-- If you notice on that chart they are 'Predictions', what I am seeing is actual changes.
WTM Sorry about your confusion, but that is how we note then down (4.3 = 4 feet and 3 inches).
All I am saying is that these do not conform to the normal pattern for Tilbury