Finally I have a working program which calculates the strength of tides based on the relative positions of the moon and the sun. This is based on the JPL ephemeris which is the most accurate available and is also used for space probes. The calculation is based on the relative distances of the moon and sun from the earth at any day over the last 60 years. The net tidal force is the vector sum of both components during their respective orbits. To sum these I take the dot product of the position vectors and apply a factor Mass/R^3 to both terms. Twice a month the earth experiences spring tides corresponding to the new moon and the full moon. This is because the sun’s tidal force aligns more or less in the same direction to the moon’s tide at new moon and again slightly less at full moon. This is then amplified when the new moon coincides with perihelion of the earth’s orbit around the sun. These are perihelion spring tides and up to 4 times the strength of neap tides.
Now look carefully at just how much the earth’s eccentricity modulates the net tidal forces. This is because the sun’s mass is 27 million times larger than the moon and small changes in earth-sun distance can have large effects. Currently the eccentricity is 0.0167 and can reach as high as 0.057 during Milankovitch cycles leading to a rough doubling of the direct solar tide. This then must also amplify the net vector lunar-solar tide as indicated above significantly. Small changes in sun-earth distance are amplified with respect to those of the moon by a mass ratio of 2.7*10^7 caused by the 1/R^3 dependence of tidal forces.
Now consider the coastal flooding this winter which has mainly effected western coastal regions of the UK. The main reason for this are the unusually strong spring tides rather than global warming. These storms have tended to coincide with unusually extreme tides. Next winter such flooding is unlikely to re-occur.