A series of maps by Registration Districts in England and Wales over the decades since registration of Births, Marriages and Deaths first started in 1837.
I've only used Birth Registrations but even so, the maps speak for themselves - in Britain, the name of GANDER, is a name with very strong Sussex roots particularly the Cuckfield Registration District.
Although the GANDER and GANDAR entries in the GRO Indexes have been completely extracted, it is now accepted generally that there are missing entries (for all names) for the period the national indexes started (Jul 1837) until about 1874 - and even after that some entries are no doubt incomplete, or missing for whatever reason.
Using only the Baptisms I've recorded from Sussex Parish Registers, I've also prepared distribution maps for the periods: 1571-1700; 1701-1750; 1751-1800 and 1801-1837. Whilst I think the 1751-1837 period is fairly complete, I know that I haven't covered every Sussex parish register and so these cannot be 100% accurate. However, when compared to the distribution pattern obtained from the later Birth Registrations, they seem quite compatible to me.
The small area around the parishes of Albourne, Woodmancote, Clayton and particularly Hurstpierpoint - all within the later Cuckfield Registration District - seems to be the main heartland of the GANDER name in Britain. Indeed most of the GANDER trees I have probably have a common origin in this part of Sussex.
There is also a major grouping in the Hooe, Herstmonceux, Chiddingly part of East Sussex however which almost vies with the Hurstpierpoint grouping. Strangely, this group - which makes up the largest GANDER family tree I have - seems to have few links with the 'Hurstpierpoint' families. Perhaps though I ought to say few known links.