In August of 2014 the pair broke out to the topside. Since late December we are in what I usually call on shorter timeframe's "buyer's remorse," although, it is harder to apply that to a timeframe like this because of macroeconomic trends and unforeseen geopolitical risks. However, the British elections are getting closer to completion, which should help alleviate some of the static for the pair.
I see a few potential plays.
1 - Let the turmoil and recent weak data play out and hurt the GBP further, then, assuming elections play out to its benefit, look to get back in around 172.
2 - Play for the bounce off a crudely drawn year-long trend line.
(I think my choice of words reveals my preference. If you play the dailies, I'd sit this pair out for now, but keep an eye out. A lot of potential here for H2 of 2015.)