I don’t think you were a dick either. Now, I won’t repeat what many others have said, but want to add this: Asking the police for proper identification (and taking down their details) is good practice even if you are satisfied that their actions are perfectly reasonable. This should be done simply to insist on accountability.
If people can and do hold the police accountable for their actions, and ascertain the legality of police measures, they are contributing to the checks and balances of a liberal democracy. The police therefore shouldn’t take this personally. You were simply doing your job –as a good citizen.
PS: liberty has a monitoring form for section 44 searches here: http://www.liberty-human-rights.org.uk/issues/6-free-speech/44-search-monitoring.PDF