C.A. & Sons was a mark used by Charles Allerton & Sons of Park Works, Longton in Staffordshire. The factory was in production between 1859 and 1942. The factory was taken over by Cauldon Potteries Limited in 1912 but continued to produce items under the original name.The number 766 would be a pattern number, but as I do not have a pattern reference for this factory I am unable to tell you the name.
Rd. No. 69456 is a registration number. In 1842 a register of designs was established. Between 1842 and 1883 a diamond shaped mark was used to identify the registration of the pattern. In 1884 the system was changed to a numerical mark and 69456 would indicate that the pattern was registered in 1887. This however does not indicate the age of the pieces you have only when the design was registered. Age could be anywhere from 1887 and forward for as many years as the pattern was in production.
Another good way of establishing the age is with the "England" mark. This was used up to about 1901 by most factories and after 1901 was generally changed to "Made in England".
Staffordshire Transferware is as popular today as ever. The majority of the production was in blue and this is still a favorite with collectors. Other colours were also used, browns, greens, purples and mauves, black and even yellow. Many of these were produced in small quantities as there were many production problems with some of the colours.
Hope this helps.