I have tried Vietnamese Sencha.
Better than Chinese but nowhere near to Sencha Uji
I have also done some research on
types of Breakfast teas.
Apparently there are 3 types: English, Irish and Scottish.
If you look superfluously, then what our Tea King Stitchawl said is correct.
English Breakfast is a strong smoky beverage ...made from Keenum Chinese black tea and Irish Breakfast is a blend of Assam and Ceylon black tea varieties
However, the reality is a bit different and more like:
the blend vary, with Assam, Ceylon and Kenyan teas predominating, and Keemun sometimes included in more expensive blends
Probably our Tea King has a better access (and taste) to the better types of English Breakfast than us, mortals.
Irish is what was said
It is a blend of several black teas; most often Assam teas
So, in the modern world it is mix and match. You must know which brand is better and hunt for it specifically.
Interesting