The K1 (2-6-0) locomotive 62005 taken as she approached Hartlepool Railway Station on March 21st, 2015 - with a group of admirers on the banking.

I was puzzled about the fine building in the background, it's the former Christ Church converted into an Art Gallery.

Yes, the former Christ Church and now the Art Gallery as you said - and a Grade II listed building:

https://historicengland.org.uk/listing/the-list/list-entry/1250112?section=comments-and-photos

Intrinsically connected to the development of the docks

"The stone was excavated from the docks being built nearby and donated by Ralph Ward Jackson, the industrialist who was behind the building of the docks and West Hartlepool."

The K1 engine as 'LORD OF THE ISLES" taken at Hartlepool Station in May, 2008.

You can also see a video of her as she leaves:

https://www.youtube.com/watch?v=rH53kWDLBUU

Photo of the Seaton Canoe end of Hartlepool Docks, notice the semi underground Bunker on the right which I remember on my Sunday Morning trips for a look around the Reserve Fleet, any idea when the Bunker was built (Wartime or Cold War?), any information gratefully received.