On holiday in Scotland a couple of weeks ago, touring the highlands in a camper van, together with two Dutch friends in their camper van, I acted as interpreter most of the time. Not that my friends don’t speak perfectly respectable English but there was the added difficulty of the Scottish accent. Back in Scotland, my accent becomes more pronounced within days. The carefully cleaned up ‘standard English’ I acquired during the years of living in London and abroad goes right out the window!
But a strange thing happened about halfway through the trip. I was phoning ahead to a campsite on the Isle of Skye to see if they had any space. The woman sounded confused and didn’t actually answer my question but just said “Yes, that’ll be fine, just come tomorrow.” My friends looked at me and I said “It’s fine, I think. We can just go tomorrow.” “Fancy them speaking Dutch!”, they said. ??? I had made the entire phone call in Dutch without realising it!
Something similar often happens in France and Spain where I inadvertently speak Italian. It’s so weird that your native language isn’t always the first to appear! There’s a link in the first comment to an interesting article on how our brains deal with multiple languages.
Does your second or third language ever pop out unexpectedly?