Here are the 5 reasons:
With David Cameron resigning, there will be a new Prime Minster - probably the flamboyant Boris Johnson with a style and views very different from the current premier.
Another fallout: it seems likely that the leader of the opposition Labour Party - Jeremy Corbyn - may be replaced because of his strong stand again Brexit.
On the horizon is the strong possibility of a new nation - an independent Scotland - with the call for a new referendum for Scotland to exit Britain and stay with the European Union.
Perhaps most explosive of all is political fallout of Britain waking up this morning to a hugely divided nation. The rise of the UKIP party, headed by Nigel Farage, and known for its ugly racism, is seen as imminent - and the spread of the the cancer of anti -immigration and racism across all of Europe with different right-wing parties finding new strength.
Add to these political challenges the economic tremors in the stock market and the Forex markets today - and Britain may never be the same again.
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