My question is, shouldn't I have stuck to pounds in the adjustment for inflation, and then for clarity expressed the adjusted amount in dollars?

Yes. (former editor resisting temptation to rant about "Editors in my day would never have let that get by ...")

...and I'm just being overly sensitive to terminology,
As any good editor should be!
Every Style Book I have seen is clear about consistancy in stories. If you start with pounds continue therein inserting (parenthetically) any comparison to another currency. This also allows another paper that picks up the story to use the parenthethesis to change the original amount into their own currency.
Pounds to (dollars) or pounds to (yen) etc.