The postal market watchdog saluted Royal Mail's "excellent progress", observing that it was two percentage points above Royal Mail's minimum target of 93%.
Royal Mail's own statistics showed that a record 94.2% of First Class letters arrived the day after posting during the July-September quarter.
The Postwatch tests were commissioned in response to concerns of business and social mailers that their experience was not consistent with Royal Mail's published performance figures.
The four-week testing period began on September 26 and involved posting nearly 18,000 items of mail (small and large envelopes and packets) throughout the UK. The test was designed by Andrew Lester & Associates.
The national figure of 95% was spoiled by variations in regional service levels, Postwatch pointed out.
The worst performing channels were South East to the North of England (85.2%), South West England to South Wales (86.7%), Wales to London (87.4%), postings in general from Northern Ireland (87.5%) and the Midlands to Scotland (88.5%).
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the Forum.
This article was first published on brandrepublic.com