Below is a table that dates the Wessex genealogies up to Alfred’s time.
The generations have been arrived at by using the following structure:
Each generation has been dated using the obit of the individual ruler who died last in that particular generation. So, for example Alfred’s obit has been used rather than those of his brothers. With Saxon pedigrees, unlike Welsh ones where the crown generally passed down to the next generation, it was not unusual for it to go to a sibling. There are gaps in the generations, for example between Egbert of gen. 16 and Ine of gen. 12 as we do not have the obits of the intervening rulers. Note, the obits of Ceawlin, Cynric and Cerdic are not those indicated by the Anglo-Saxon Chronicle but instead the values obtained by Dumville’s correction. The zero generation is that ascribed to Woden, unlike the tables for the British kings which uses Arthur’s generation. The two sets cannot be synchronised since they have differing generation step-sizes.
The analysis shows that for Wessex the generation step-size was 26.7 years. The deviation column shows how far the individuals obit differs from that ascribed to the generation to which he belongs. Most deviations should be less than half a step-size and indeed this is the case.
As Sisam noted Elesa/Esla and Giwis/Wig are alliterative pairs for the same individuals. To this list has been added another pair, namely Creoda/Cerdic. The generation obit values for Elesa to Woden are estimated values using the step-size given above. It will be noted that Esla was a contemporary of Arthur. This together with the similarity of names allows us to be fairly confident that he was Osla Gyllellfawr. Sisam points out that the name Esla is unknown in English. This may indicate its British origin. He says Elesa is also unknown unless it is etymologically the same as Elsa in Widsith.
The postulate that there were two Wessex dynasties resolves the paradox that although the ASC tells us Wessex originated from the South coast with Cerdic, the oldest Saxon sites are around the upper Thames valley and the founder was a Giwis.