I'm pretty sure it's a Mk1 Seawolf 26 - I have one! But the washboard is much bigger and the mainsheet track is different - see photo of mine when I bought it 27 years ago. Otherwise all the fittings look the same as mine. Mk2 Seawolf 26s had a much higher coachroof and longer boom.
Here's a more recent photo of my hatch and main sheet arrangement. It's a bit of a climb to get over the bridge deck and down into the main cabin but if she ever gets pooped, nothing is going down below. If water does get in, she has already sunk!
It's original. It was the second boat David Feltham built. He came on board many years ago at one of our rallies. He built the first Seawolf 26 for himself. He wanted something to race in the Round the Island Race. At the time, he was building the Cobra series of yachts.