When you're talking about Britain's greatest ever anything I think you have to set the bar high otherwise you'll end up considering a lot of people that just don't deserve to be part of the debate. I reckon Turpin would have found Eubank the easiest of the three to deal with. If Turpin fought Eubank the way he fought Robinson then Cwis wouldn't have been able to handle the constant pressure. I think Watson would have given Turpin the most trouble but in his prime Turpin would have beaten the three of them in their prime; Watson and Benn would have been stopped, Eubank might (just might) have gone the distance due to his chin but he would have been badly beaten up.
I think Minter is a definite contender for Britain's nicest world champion. He always seemed such a nice bloke when he was interviewed.
Let's not forget Sr said Jr would beat (actually WRECK) Golovkin, Ward and the rest of the Middles and Super Middles so you might have a case. Jr doesn't have to actually beat any of these fighters, him or his Father just has to say it and it's true. It's what I like to call the "Eubank Effect"
The jury is still out on Chris Jr. But he looks nowhere near as good as his father thus far and he's 30 soon. Sr made Benn and Watson look silly for portions, at 24.
The facts are that he beat Benn and Watson fair and square, looking far superior to both in terms of boxing; making them miss frequently and landing almost at will. It was Benn's huge body shots out of the clinches (and uppercut out of clinch that split his tongue) that pained him, and his own sloppiness later in the fight against Watson that caused him to fall in off-balance from the dehydration/weight-making that allowed Michael to land a few shots and take a few rounds. But it was complete domination from Eubank early (the great McCallum landed only body shot counters til the later rounds on Watson). DeWitt was coming off a great win over Matt Hilton and gave a peak Hearns a very close fight in every round. They couldn't dent him (Hilton was supposed be the best left hooker in the game) and Benn obliterated him, nearly had him out in the first. Barkley could've been given the decision over both Duran and Nunn (on aggression) for the WBC and IBF versions in his previous two fights. Duran the greatest fighter ever and Nunn the lb4lb best at the time. What Benn did to him was ridiculous.
It's a huge complement to have a top 10 all-timer in McCallum give his fighters at Top Rank gym tapes of Eubank and ask them to study the ring generalship, citing that were very few - if none - who mastered it better.
It was hotly debated because the whole country hated Eubank. In reality, Eubank won the first nine rounds; the first five easily. It was only his dehydration from weight-making that gave Watson a look-in. It was looking like a shut-out for a while, very easy.