Are you refusing to understand what I am saying or what?
The time it takes for the sun to go from the highest point on its orbit (as seen on earth) to the highest point of its next orbit is marked as 24 hours. Until 1956 the 1/86400 part of this timespan was marked as a second.
We now know that what was marked as 24 hours until 1956 was not always exactly 24 hours due to differences in the rotationalspeed of the earth around its axis.
The tendency even seems to be that days are getting longer and that they were shorter in the past. This tendency can be shown true for about 30 years I guess with the by you so holy data.
Shorter days in the past and thus shorter seconds in the past are a perfect explenation for higher measured values for c in that same past.
Do you understand now?
If not feel free to ask, and will try to make it even clearer.
When you claim that the lenght of a second was not based on the lenght of a day in the past, then I have to tell you that you are wrong. Look at the Wiki encyclopedia or Google and you will see that I am correct.