The neighbours at our previous house in Somerset had the builders in to do some re-pointing to the side of their house. They used bags of hydrated lime instead of hydraulic lime and wondered why after pointing the house for a week, the mortar was not setting.
^ I'd guess builders will use NHL, as it's closer to cement to work with.
It's probably worth finding out though, if nothing else jsutbto check they aren't sneakk in a bit of Portland, as aunt_maud says.
But yeah - soft reds only really get damaged when someone has reported with a cement mortar.
Or that awful dyed brick repair crap that someone has slapped on my place