There is no apostrophe in the plurual of parent (parents) Viaduct, so why have you put one in? You said something about educated people?
Didn't want to make you blush Dave. You're quite right about the state of literacy in the UK, not just Dawlish. If you want to either laugh or cry at how extreme a problem this is, try looking at any auction on Ebay. I can guarantee 99% of the descriptions will have the most cringeworthy errors. ( just spent 5 minutes checking this post for grammar......think it's ok? )
Pot and kettle Dave?
Grammer is actually spelt grammar!!!