A sharp fall in the value of sterling before the release of U.K retail sales Thursday has prompted suspicions of a data leak.
Selling versus the dollar took place just before the Office for National Statistics (ONS) released the data at 08:30 GMT.
Subsequently, news hit the wires that U.K. retail figures for March fell 1.3 percent month-on-month, failing to match forecasts.
Reuters Buzz, which offers analysis and commentary for the foreign exchange community and is compiled by foreign exchange analysts, has suggested the trading pattern looks suspicious.
When contacted by CNBC, the ONS said it did not comment on market rumors.
Further selling after the release then dropped the pound down to a session low, although sterling has since recovered.
In December 2015, selling of the pound also took place in the 30-minute window prior to ONS wage inflation data.
That prompted one newspaper report to claim that some city traders believe someone at the ONS is guilty of leaking data.