In a forum I frequent there are many times that contractions are used in a way that's unusual, and many users find to be ungrammatical:
"I've to" etc.
To me it's not ungrammatical but it sounds both old-fashioned and like something you might hear in certain rural areas of England, but I don't know where.
Do some of our English experts here have more information on who uses or used this structure? Which region or regions and which age groups etc?