Bombing MI6 is not going to make you popular, and will almost certainly lead to your arrest. If you were thinking about it, don't. If you want further proof that it's a bad idea, you need look no further than the arrest of two Welsh chaps with too much time on their hands. Apparently, two men, aged 21 and 52 (father and son) were detained by local and Metropolitan Police in Wales on 28th July when one suspicious parcel was found at the M16 Building (whether it got inside is unknown) and another suspicious parcel was discovered at a South London sorting office early on the morning of the 29th (we're not given its destination)! The article notes that police were granted "extra time" to question them this afternoon. Crikey.
All that I've written above has already been released by the AFP, who simply issue simple news items without further embellishment, but it does pertain to this area, and I'm sure we'll all hear more as it unfolds! The Daily Fail has a little more info, saying that the men are being questioned at Padding Green "secure" police station in London (Queens Park) and that the bombs were "amateurish" (neither had to be destroyed in a controlled explosion, which rather implies that these were not serious bomb makers).