New post pin to top

My latest post does not go to the top of the page.

For some reason the fourth post in my list pins to the top of the page. It is not marked sticky! If I change this fourth post to ‘pending’, another post then replaces this at the top of the page – not the most recent.

After the post at the top of the page the most recent post then starts (the sidebar widget also starts at this point).

Can anybody help me to understand how I keep recent blogs at the top? Thanks