SEWANCKE surname - what should it really say?

[casalguidi]

I have just received a marriage certificate and, unfortunately, it is not a photocopy of the original but transcribed by the local registry office.

One of the witnesses (or so it says) is Charles John SEWANCKE.  I am certain that the surname is a mistranscription of something else................. any ideas?

I've been researching this family for well over a decade and the name isn't even remotely familiar.  He could have been a church official but it would be nice to find out.

Even a WWW search comes up with nought!

Incidentally it's Folkestone, Kent 1878.

TIA

[Tati]

 Perhaps not very likely, but the name 'Schwancke' exists...
Tati 

[casalguidi]

Quite possibly that is it then.............. or something very similar

Thanks