From the recruiters I talked to recently, it had no effect. From the interviews I had recently, it had no effect. Still recruiting and expanding.
One of my past company recently interviewed with journalists to announce that they are extending their operations and opening a new office in the USA. The next day the news published an article "<company> is leaving the UK after the Brexit". I'll let you imagine the surprise when we discovered the article the next morning. That's just 100% wrong and misleading.
I'm now willing to extrapolate that 90% of brexit announcements are fake invented by journalists for sensationalism. Nothing is happening, really.
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Regarding the GBP exchange rate.
As in all the major cities in the world, most of the income goes to pay the rent. The rent is in local currency, unaffected by USD-EUR-GBP rate.
We might hit a +10% on food price (and gaz) in a near future. It might get harsh[er] for big families and low income jobs, it's fine for people with good salaries. (Not to mention free catered lunches at tech jobs :D)