Sterling has not been at these levels since 1985 - BBH

Research Team at BBH, suggests that the Sterling has not been at these levels since 1985 and it is difficult to extrapolate what price will bring in supply or demand. 

Key Quotes

“We must imagine that any long position that had a stop in the market was stopped out.  Of course, not all positions are protected with stops.  In addition, those who sold calls as a hedge have maxed out as the call will not trade below zero (different than interest rates).  

There may be some levels that have psychological significance like $1.30 or $1.20 or even $1.00.  At $1.30, sterling would have declined by about 13% from its pre-result high.  While we thought since Cox's murder that the Remain camp would win, we recognized that a vote to leave would send sterling sharply lower.  We anticipated a 15-20% slide in sterling.  From the $1.50 level that would target $1.2750 (15%) and $1.2000 (20%), which still seems reasonable.”