Bird call at night - river Stort

Hello! Apologies new here but wondered if anyone could help? 

I live on a narrow boat and am currently exploring the River Stort in Essex, moored nearish Harlow Town station in some woodland near to open fields. Tonight after dark I started hearing a really distinctive and striking bird call I've not heard before - a repeated 'ee-oo-itt' type call every 10 minutes or so that seemed like it was from the trees above. I'm not experienced with bird calls at all but sounds like a bigger bird - definitely not a tawny owl as heard those before and dosn't seem to quite sound like any other owl recordings I've played from online clips though. Anyone any ideas? Seemed to sound closest to red kite but still not quite right.