Too much resistance above, reverses the pair back toward unchanged
The GBPUSD rallied higher in Asian Pacific trading  and in the early London session, but ran into some technical resistance near the 200 hour MA and the 38.2% retracement of  the move down from the November 19 high. Those levels came in at 1.51236 and 1.5130 respectively (at that time). The high price stalled at the 1.5125 between the two.  Later weaker PMI data helped to push the pair lower and the price has been drifting lower since that time.