1) In the Introduction, please provide a brief summary, by section (or where necessary sub-section), of the paper. This would be very useful to readers as an overview of the paper structure, so they are prepared when starting to read the full content.

2) Note that use of a decade-long (1950-1960) period of the CRU TSv.1.2 time series introduces a risk of significant interdecadal internal variability 'aliasing' into the validation procedure. Ultimately, a standard 30-year independent validation period would have reduced this risk somewhat.