It's fine to focus attention on one individual who was detained and questioned by British authorities at Heathrow last year, but without a recognition of how often British officials use their detention and questioning authority at ports of entry and transit, what happens to an individual lacks context.
Of course, sometimes that lack of context is deliberate.
According to varying reports, between 60,000 and 70,000 people were detained and questioned at British ports of entry and transit during the 2012/2013 period studied. Most of these incidents required less than an hour for resolution while some 40 or so required 6 hours or more to resolve. There were as nearly 700 detentions (one assumes longer than 9 hours, the length of time British authorities can hold someone without actually arresting them).
There has been extensive reporting regarding what's been characterised as the overuse of Schedule 7 of the Terrorism Act of 2000 -- which has led to tens of thousands of travelers being detained and questioned under the Terrorism Act, even if there is no reasonable suspicion that they are terrorists.
Understanding how often and how broadly this statute is applied aids in understanding what needs to be done about it.
A "journalist exception" is probably not the answer.