In an article in Suffolk Review in 1970 (vol.3, no.8, pp.286-292), R. J. Elliott published this text without specifying his source, and presenting it as fact.  It can now be found copied onto several websites.

> In 880 A.D. a Norseman by the name of Gisli brought his long-ship ashore at Frostenden, then on the coast of Suffolk; pushing a few miles inland he settled at what is now Gisleham, literally the home of Gisli, not far from Kessingland. Thirty years later, in 910 A.D., one of his sons, who would have been named Gisling by Norse custom, is said to have pushed westward and started a settlement at Gislingham – the home of Gisling.

The Anglo-Saxon Chronicle does not mention Gisli, and I can't think of any other source for this period which would have precisely dated events like this.   So my question is: where might Elliott have got this mythical account from?