That remains to be seen. First of all, JA is (supposedly) granted full
Diplomatic Immunity by the nation of Ecuador, of which he's now a formal
citizen. Not by the U.K. It is not a matter (as suggested by the Guardian)
that Ecuador has to request the U.K. for ANY permission. The U.K. may deny to
respect JA's diplomatic Immunity. But then it may ONLY expell him as persona
non grata, nothing else. Both nations are signatories of the Vienna convention
(1961), and have principally to abide by that convention, not withstanding the
fact that the U.K. has only partially ratified the treaty. If the U.K.
declares him p.n.g. they can demand to escort him out of the country. If they
do arrest him (as he's a diplomat now) the U.K. takes the considerable risk
that Ecuador will detain all British diplomats currently present in Ecuador.
And I happen to doubt if they would want thát.