The pound isn’t participating in the yen rout in the way most other currencies are. This chart shows why:
GBP/JPY daily chart
I think this chart is keeping broader pressure on the pound and leading to some broader softness. If it breaks out above 154.20, look for broad GBP strength. The pair has had a chance to consolidate since the initial rally from 148 so there is a chance it could breakout before the weekend, especially if risk appetite continues to improve.