Ticket Refund Rights with British Airways After Terror Alert Raised at Destination

I am aware that flight cancellation and refund issues are generally covered by the specific conditions of carriage associated with the ticket. My question has to do with British Airways in particular however if there is reference for where it is extended for airlines traveling to the UK and USA it would be helpful.

I have a funeral to attend in London on the 22nd and 24th of this month. As most are aware, UK has been hit four times by violent terrorists within the past three months including thrice in the last two weeks alone leading to the threat level in London being raised. It was raised after the first attack to the highest level, and then lowered after which the second attack happened just yesterday. The USA has also issued travel warnings for UK.

The US has issued warnings to its citizens about travelling to the UK and continental Europe this summer. An update from the State Department, issued on Monday evening, warned that Isis and al-Qaeda ‘have the ability to plan and execute terrorist attacks in Europe’

Is one allowed to cancel flights to the destination without penalty in events like this? Is there some general legal precedent establishing this, i.e. a terror attack as a material event? I am asking more for precedent than opinion.

UPDATE: June 4th

Malaysia Airlines has told customers they can get a full refund for any flights booked to London over the coming days in the wake of Saturday’s terror attacks

London terror attacks: Airline offers full refund on flights to London in days after attacks

For the Brits who seem strangely indignant or upset about this question, this is not and has never been a question about whether the USA where I live is safer than London/UK. The statistics are abundantly clear on that and known to all.