We can see a strong JPY these days and it makes almost all pairs related to JPY into bearish trend. GBPJPY is also not an exception especially when we have a weak GBP also in it which has been so unstable nowadays because of Brexit.
According to the figure, the price shows some respect to support levels which are made upon weekly Fibo levels, first one around 166.40 and now around 157.30. Cable shows more strength from itself in other pairs, maybe it can make more serious retracement here especially when it is on strong support. For upward movement, 38.2 level of Fibo around 166.40 could be a reasonable target.