Why were there protests in Britain against Iran?

The British Defense Ministry says Iran forced eight British servicemen and their three patrol boats into Iranian territorial waters before capturing them earlier this month. The eight were held for three nights amid growing British protests before Teheran ordered their release.  Iran said the captives were released after Britain admitted the boats were mistakenly off-course.  Britain is continuing to negotiate with Teheran for the return of the three boats and other equipment seized June 21st.