* Prior to Brexit, I reckon the UK's main selling-point to US and Asian multinationals was that it's a perfect beachhead into mainland Europe, namely as everyone speaks English already, so localization (well, localisation) doesn't need to be a concern at-first, and allows companies to test-the-water by marketing locally in the British Isles before expanding into the rest of mainland Europe.
* As the UK's regulatory environment was in the EU it meant that getting sign-off from British regulators (again: where language and cultural-barriers won't be an issue) is more straightforward as you don't need to seek regulatory approval in every EU country, only 1.
* Extant supply of highly-qualified, if not world-leading, scientists, researchers and engineers and access to its higher-education system - and those researchers and engs would have included more of mainland Europe's best too due to greater academic collaboration within the EU.
Post-Brexit: all the UK has is... speaking English, and that's it. Now non-EU companies need to seek regulatory approval in both the EU and UK - and the EU's market is considerably larger.
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I reckon within a decade the UK will find some way to rejoin the more important parts of the EU in-all-but-name, including (possibly!) even joining Schengen to alleviate all of the issues with labour shortages, tourism, and the rest - as well as seeking de-jure regulatory alignment - because the UK is really not the super-desirable market the Daily Express likes to believe it is.
I also sincerely believe the UK will also likely rejoin the EU proper - probably within a generation from now: the age demographics of the leave and remain demographics are stark - it's even been said if the Brexit referendum were held 2 years later then remain would have won simply because enough members of older generations (which lean heavily Leave) would have died off.