The total value of watch sales in Great Britain fell by 1.3% in October, the first year-on-year dip since December last year, according to GfK data.
The watch industry drop is the same as the wider retail sector, which saw YoY sales fall by 0.3% in October, according to the Office for National Statistics (ONS).
Higher inflation dampened spending, the ONS said, and that October last year had seen very strong growth.
October 2016 was also an exceptional year for the GB watch industry, with sales rising by over 27% in the month as the weakness of the pound gave UK retailers a massive price advantage over rival international markets. It was also the last month before Rolex raised its prices by 10% on November 1.
The average price paid for a watch in Great Britain was up by 12.5% in October over the same month in 2016, half the rate for the year-to-date, which has seen average prices rise by 25% compared to the January-October period in 2016.
The annual average price rise is expected to drop even further in November when comparisons are made to the month after Rolex increased prices.
The value of watches priced at over £1000 rose by 53% last October, and London sales rose by 55% as wealthy tourists flooded in or bought online from British retailers.
The market for cheaper watches has stabilised this year, with year-on-year sales dropping by around 10% each month since January.
Last month was the first since WatchPro has been publishing the monthly GfK data that London has performed worse than the rest of Great Britain.
The value of sales in London dropped by 8.2% in London, while for the rest of Great Britain sales rose by 4.4%. Harrods closed most of its Fine Watch Room after summer as it remodels the space and doubles its size. It is expected to partially re-open later this month.