There were two bits of news that have led to this recent price movement. Both had a strengtheninig effect on the GBP/JPY and they were released within minuted of eachother. From Trade the News:
1401GMT: JPY weakens after joint central bank liquidty announcement
and
1404GMT: (UK) BOE expands range of collateral at three month maturity
1401GMT: JPY weakens after joint central bank liquidty announcement
and
1404GMT: (UK) BOE expands range of collateral at three month maturity