So, we woke up on Friday morning to a world that had changed. Facing change is one of the most difficult things to do. And leaving the EU will change Britain completely. That’s why if, as an investor, you’re feeling a little concerned, you’re not alone.

I, and other commentators, are just beginning to work through the implications of the dramatic strategic about-turn that Britain took last week. What will this mean for the FTSE 100? What about individual shares?

We’re still working through the Brexit implications

Clearly population growth in the UK will slow if immigration is reduced, as will GDP growth. It’s likely that there will be fewer jobs, and the employment rate won’t be as high as it would have been.

Yet many things will remain the same. People will still go shopping. Companies will still function, and indeed a falling pound may help exports. Remember that the country has been booming up to now. And even if growth slows, the Bank of England has several weapons in its armoury to help the boom continue, notably QE. That’s why I think predictions of a recession are wrong.

Some companies will reduce numbers in this country, but for many firms it will be business as usual.

What about the house builders? The share prices of Barratt Developments (LSE:BDEV) and Persimmon (LSE:PSN) have taken an absolute battering in the past few days. Late last year Barratt Developments stood at 650p, but the slide downwards has been gathering momentum, and each share now fetches just 355p. That’s an almost halving of the valuation in a few short months. The picture is similar for Persimmon, which has tumbled from a high of 2,062p to the current level of 1,315p.

But falls have opened up buying opportunities

My view is that these falls are overdone and reflect more sheer panic than a reasoned judgement of how much these companies are worth. Take a look at the fundamentals and you’ll see what I mean. Barratt’s 2016 P/E ratio is just over 8, and the dividend yield is 6.92%.

Similarly, Persimmon’s 2016 P/E ratio is 8, with a dividend yield of 7.24%. By anyone’s reckoning, these are bargain prices. Yes, I expect the rate of growth of the housebuilders is now going to slow, but there’s too much fear in the markets.

That’s why I suspect that the current panic has created a buying opportunity. If you were to invest in these companies near the bottom, I think in a year or two’s time you’d be sitting pretty. Because these are still highly profitable, cash-generative firms with strong prospects. Brexit may have taken the edge off the growth, but these businesses are still worth buying-into.

Whenever there’s a scare, whenever there’s a crash, things can look terrible, and it seems the world is about to end. But, believe me, it won’t. This EU exit will take years to work through. And Britain will find  a new path to prosperity.

Viewed calmly and coolly, Barratt Developments and Persimmon are now contrarian buys. You see, in these situations you must use your head, not your heart.

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Prabhat Sakya has no position in any shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.