Buy sterling now?


Yes. Your logic would suggest that sterling should have fallen through the floor last Thursday when the BOE lowered the Bank rate by 50 bp to 1.5% thus increasing further the yield differential between sterling and the euro. The opposite has happened !
 
I think a larger cut was expected by the BOE and because the ECB rate announcement was due this week the speculators have pushed the Euro down in expectation of a larger cut than 50bp.