The travel history to UK states if you were refused a visa to uk. Our last vist visa which got refused and then we complained to MP and complained to UK visas and immigration complaint department and then our decision was overturned. So is this still considered visa refusal for that part of application and in notes to state that visa did get approved after complaint ?
It is still a refusal. You should declare it and explain the decision was overturned. UKVI will obviously know that, but you still need to declare it.
I have a friend in the same situation. She has stated the refusal in her two subsequent (successful) applications. Better safe than sorry. It will not damage the credibility of the current application.