The Union flag flies at half mast in Whitehall, central London, on June 4, 2017, a day after terrorist attacks on London Bridge and at Borough Market. Stefan Rousseau / PA via AP
The Union flag flies at half mast in Whitehall, central London, on June 4, 2017, a day after terrorist attacks on London Bridge and at Borough Market. Stefan Rousseau / PA via AP

Was it prudent to dial down the UK terror threat level?