British Whites make up 85.6%, Irish (as in from the RoI) make up 1.2%, so overall 87% (rounded) are from the British Isles
Including the Irish as being the same is a legacy of Empire. Yes, they are now culturally extremely similar, but its still an increase in diversity in history, increasing the number of Roman Catholics for instance. Irish is to British as, say, Korean is to Japanese.
...and the remaining 5.27% will be from either the United States or the other 3 Anglophone countries, which make-up a kind of cultural continuum.
Firstly, you're getting confused between nationalities and ethnicities. A British-descended Australian or South African would mark their ethnicity down as one of the British nationalities. Secondly, you're simply wrong. Most of the non-British, non-Irish whites are immigrants from the Europe Union's free travel area: originally a lot from France and Germany, but over the last decade from the new joiners, particularly Poland. No doubt over the next decade they will be joined by Greeks and Portuguese looking for jobs.
As for Indians, well yes, counting them as one group would be comparable since their is really no such thing as an 'Ethnic Indian', rather their are dozens of ethnicities from India.
"Whites" are a race. "Indians" are a nationality. The equivalent to "Whites" are "South Asians", i.e. inclusive of Bangladeshis and Pakistanis, which almost doubles the numbers you quote.
Regardless though the point stands that, aside from the Scottish, English and Welsh, which together form the British Panethnicity, Britain has historically not been diverse, and the OP was talking about changing the past to create long standing minorities, not having them decide to adopt very open immigration policies.
Point mostly accepted. But don't long-standing minorities become part of the "panethnicity" most of the time? i.e. Manchus in China, Bretons in France etc...
Not my fault the people who run the British census are criminally slow (results won't start being available until Sep. 2012, and won't be fully released until 2014).
Agreed it's a fiasco. But we need to take it into account when judging these things. I would guess the number of non-British, non-Irish ethnicities in the country is currently around 15-20%.