BREXIT, Bumbling idiot Boris v's incompetent May. Pound can't stay at 1.3/US dollar long.
Failings with the EU, Incompetence from Theresa May and now the political theater from Bumbling Idiot Boris Johnson (the home of the mess), likely in a last ditch hope of achieving his ego's dream of being Bumbling Incompetent PM in Chief leads to the opinion FIND A DIFFERENT CURRENCY, PRONTO.
Trump's UK visit and EU bashing may have sustained the 1.3/US dollar, but this valuation is very unrealistic in the current circumstances. Trump turmoil in the US may also have retained the value. Either way, the more the turmoil clears, the bigger the drop in value.