Bouyed up by your responses to my last piece, I've been more confident in trying out my conversational German. Last week at a relaxed outdoor social gathering, I ventured forth with a whole handful of new words I had learned including lagerfeuer. I was trying to find a clever way to somehow drop it into conversation and was waiting for someone to light the fire so that I could remark how lovely lagerfeuers are, when someone broke into conversation with me in German about as good as my own. This time it was my turn to reply to someone's brave linguistic efforts by asking if he was English. He was Welsh. Served me right. But, he said, he had moved to Berlin after living for years in London.
Excited at finding a like-minded Londoner, I looked for common ground. Why had he moved? Was it, like me, for the high-quality and varied sausages and lack of CCTV? No, he said. It was because his wife had been freaked out by the terrorism after the 7/7 tube bombings. They had lived in Kings Cross, which was the site of one of the explosions. She wanted to live in a safer city. Berlin.
Only a few days later and the newspaper headlines were screaming terror warnings. At first I wondered if our conversation had somehow been responsible. Then I thought about what his wife would say. Would they now be moving on to another city?
The sudden shock of the news made me realise how relaxed I had become since moving here without the obvious terror threat so persistent in London. I remembered that July day in 2005. Trying to get on the tube, thankfully an hour later than usual, being told there was a power failure, cursing London Transport. And then slowly realising the horror of it all. I remember taking my first tube ride a week after the bomb and noticing how empty it was. I thought I had left all that behind. But here it is, joining the party in Berlin. As we should all know by now it's a global problem. There isn't anywhere you can really run to, because all the transport systems are targets.
When I was growing up we lived under a constant threat of terrorism. The IRA were always bombing - or threatening to bomb. I don't know how or why, but we just got on with it. There wasn't anything like the hysteria and paranoia that there is about this lot. Was it the same for you when the RAF Baader-Meinhoff brigade were at large?
A few years ago I had a conversation with a very high-up official in MI6, Britain's secret service. I asked them if we weren't really overreacting to the Islamist threat. That all the CCTV and surveillance and fear-inducing statements were disproprionate. Wasn't it much, much worse when the IRA were conducting their bombing campaign - with regular attacks that were random and real? He expressed some sympathy for my view.
So I was surprised by my slightly panicked reaction to this new Berlin terror alert. Suddenly I felt like I was back in London again. Looking over my shoulder on the U-bahn. Wary of black rucksacks and checking out the people carrying them for signs of nervousness.
I started thinking: should I avoid Christmas markets, the U-bahn, the S-bahn, the Hauptbahnhof and anything else with a "bahn" in it? Should I keep away from the Fernsehturm (which I walk by every day) and other tourist attractions? Where is the safest kiez? Should I move there? Should I be arguing for CCTV after all?
Thankfully the feelings subsided quite quickly - at about the same time they started putting up protective barriers around the Reichstag.
If Berlin's going to import a bit of terror panic, perhaps we need to import something of the Blitz-inspired response invoked by some Brits to combat the threat too. After the 7/7 attacks the words from a 1939 morale-building poster "Keep Calm and Carry On" started appearing everywhere: on T-shirts, mugs, posters. Here's our chance to come up with a Berlin equivalent. Any suggestions?
You can email Mark at email@example.com or follow him on Twitter @DeutschMarkUK.