Freakish figures with quirky mannerisms and odd names - Mrs Halfstairs, Captain Constable - lurk in skewwhiff little rooms or down narrow corridors lined with ancient, mildewed ballgowns.Skewwhiff - a word I've used all my life but never seen written. I would have expected it to be skewiff, so I searched for that spelling.
Wordnik has some citations of this spelling, but no definitions. A not-too-persistent search found some discussion of this spelling, but no authoritative definitions.
Skewwhiff, however, appears on lots of dictionary sites. The Longman Dictionary of Contemporary English defines skew-whiff as not straight (=crooked) and points out that it isn't used before a noun. But note that Peter Kemp in the quote above has used it before a noun.
The Urban Dictionary has two spellings - skew-wiff, meaning all messy, disheveled. Colloquial British term somehow derived from "askew"
and skew-whiff, defined as turned or twisted toward one side. Common usage in the UK.
My mum came from Edinburgh, and in our family we still retain a few northern English, lowland Scottish expressions, so I think that might be why we grew up saying this word.
The Viking Network relates the word askew - which we didn't use - to skew-whiff and says they're both of Scandinavian origin.