Petrous Ragout aesthetic oval platters

Sergio bought this pair of dishes to Dorita Ferrari almost a year ago. He knows I love aesthetic design. These ones have the aspect of being very old; they are not white, as the time had produced some degree of oxidative deterioration and the very cracked.
They transfer pattern plate with raised decoration on the rim. The decalcomania pictures - decals for short - were mostly bought from specialised firms. The collection includes decals supplied by German firms such as Zierdruckanstalt Lindenruh in Lindenruh-Glogau, E. Wunderlich in Waldenburg-Altwasser and Buntdruckerei für Keramik Carl Nitzke in Leipzig (https://geheugen.delpher.nl/en/geheugen/pages/collectie/Decoraties+Maastrichts+aardewerk%2C+1836-1969/Decalcomanie). Looking to patterns on that web page I thought that this particular one was created around 1878-1898 but studying about the the mark I ought to change my mind.
Mark with an impressed Sphinx (for the name of the pottery works) and a copy of the British Royal Arms. The initials 'S M' are likely for 'Sphinx' and 'Maastricht' (https://www.thepotteries.org/allpotters/850b.htm) In 1879 the image of the sphinx started to be used as a company mark and logo. Since 1899 the company was called De Sphinx. There, in that website you can observe a plate with something that seems very similar to our trays… the border with the knotted rope and the two hemicycles the anchor, that has the impressed sphinx and number 11 also deeply impressed, these ones has number 10. In the site (https://www.infofaience.com/en/marks/sphinx-marks) Infofaience, the pseudo England mark is said that has been used between 1906 and 1929 as an export mark. Thus, these pieces are probably from the beginning of 1900 though the aesthetic style and the state of conservation indicates that they must be older. In fact, after looking for a while I found that the pattern name is Marines and there are in blue, green and red, they have little differences because some have a circle instead of the star or lack the anchor, most of them are said that were produced in 1894/95, so the date is that 1900 ± 10 years. It measures about 35x25 cm.