Ned Rumpeltin, European Head of FX Strategy at TDS, point out that GBP/USD could rally toward 1.51 with a win of the “remain” position in Thursday UK referendum , but warns that further upside would require an improvement in fundamentals.Key Quotes:“Cable’s surge in the final days before the EU referendum has squeezed most of its scope to rally if the final vote shows a Remain win. Our reading of the available evidence agrees that the Remain camp will carry the day,but we believe the margin of victory will be more narrow than the sharp rally in GBP—and drop in vol—might imply.”“In short, we think cable’s sharp rise over the last several days has largely sapped its ability to rally substantially on a Remain win. Sterling can—and likely will—still pop higher on a vote to stay an EU member, but our ambition is considerably more limited than it had been.”“The key attractor for further topside progress comes in at 1.5118 for GBPUSD. This level represents the 38.2% Fibonacci-retracement level of the entire down-move between the July 2014 high (1.7192) and February 2016 low (1.3836). Above this mark, we see (lesser) resistance at 1.5242 and 1.5336, which correspond to local highs in November and December last year.”“A Remain win should take GBPUSD toward resistance around 1.51, but gains from there will require further improvement in the UK’s fundamentals, where we are already fairly priced.