The lede could wo with a couple more sentences, peraps focusing on her Service history, ie the Jubilee and so forth.
Done
What type of vessel was HMS Achilles? I would suggest detailing what Achilles was, so that there is more context for the creation of Minotaur.
I've added that she was an ironclad.
Note needed on usage of ironclad/armoured frigate
You were quite a bit quicker than I anticipated to start this review. Done.
Do we know what qualities caused her to be "unhandy under steam and practically unmanageable under sail"?
Sort of. Combination of poor water flow around her rudder and not-very-responsive manual steering.
'at a cost of £250[Note 1] each' - I would move the note to the end, as having it next to the price, while understandable, does make it look rather awkward with only one more word before the end of the sentence.
Done.
'She was one day too late to participate in the Bombardment of Alexandria in 1882.' - At the moment, this sentence comes a little out of the blue and lacks context. Why was she late? Had she been ordered to Alexandria with the rest of the bombardment fleet and lagged for some reason, or was a she a late addition?
Don't know, nothing I have on hand discusses the context of the bombardment to answer those questions. Probably best to simply delete the reference.
The stern view of the Minotaur is rather large at present and cutting into text where it is currently positioned. I'd suggest making it smaller and possibly movint it to the right.