The couple have recently been discovered to have been claiming expenses as MP's. to rent a London flat that they own - or rather that a family trust owns. The property was put into a trust to avoid inheritance tax.
They have been doing nothing wrong apparently, but some of Sir Nicholas's constituents are not too happy: Macclesfield Views on The Winterton Expenses - but he will still get re-elected -as would one of St Helena's donkeys if it were nominated in his place.
Clearly Mrs Winterton will, as part of the parliamentary delegation, have all her expenses paid. I assume Sir Nicholas will be paying his own way.