(Do we have usable remains of
> continental Anglian and Jutish?)
Probably the earliest document written in what might be interpreted
as Jutish (it has instances of the typical loss of final vowel) is
the Jyske Lov (Law) of 1241, written in Flensburg, now just inside
Germany. The latter should tell you what happened to (Greater) Angeln
(prob. = Schleswig), after it was abandonned by the Angles, it was
colonized by Danes. On the other hand, the Danish dialects south of
the present border which were recorded before they died out, were
rather deviant: pl. distinguished from sg. in verbs, umlaut in the
present (sg.) of some strong verbs: at stå. han stær, at gå, han gær
(the further south the more, -st in 2nd sg., in short, very
conservative as expected from a threatened border dialect. I don't
think anyone has analysed those dialects (eg. Fjolde-mål, German Viöl)
as preserving Anglian relics.
>
> Richard.