Dendrochronology (tree-ring dating) is a well-established science in Britain. Progress has been rapid over the last 40 years or so, and most parts of the country now have well-replicated oak chronologies against which to date oak timbers.
Some parts of the country are more difficult than others, for example in East Anglia the oaks have in the past grown to sizes suitable for large structural timbers in 50-60 years, whereas a similar sized timber in, say Worcestershire, might contain 150 rings.
North West Wales has also proved to be an area where local chronologies have had to be built up over many years, as sites there often do not match other parts of Great Britain well.
This is important because the patterns of varying ring-widths need to be firmly matched against the reference material in order to be sure of establishing the date.
With short sequences, several statistically significant matches may be found which are not at the correct position.
In practice, dating occurs when a new series is matched (both by comparing visual plots and statistically) consistently against a range of independent data sets. However, as more work is done the success rates even in areas such as East Anglia and North West Wales are getting higher and higher.
We also deal with imported timbers, mostly from the Baltic area, and these include structural pines from the early C17th onwards, and oak boards used in chests, doors, panel paintings etc.
Dan has extensive experience of dating several species in North East USA, and we are beginning to accumulate evidence for some timbers being imported from this region from the early C19th.