"There were lots to do" vs "There was lots to do...": is the backward existential still used?
'lots' can be singular or plural depending on what the speaker is talking about.
eg We'd better get started. There is lots to do. (i.e. a great deal, much, uncountable)
Are there any sandwiches left? Yes, there are lots in the fridge. (i.e. a great number, many, countable)