This site is dedicated to the historical background of Plot elm (Ulmus minor 'Plotii') and information regarding historic and current distribution.
For a thorough overview of Plot elm, the Wikipedia page: https://en.wikipedia.org/wiki/Ulmus_minor_'Plotii' contains a lot of information as does the excellent write up here: http://www.resistantelms.co.uk/the-plot-elm/.
Plot elm was relatively rare even prior to the advent of Dutch elm disease and is no longer known to be present as a mature tree, though there are several stands of young trees and undoubtedly many hundreds of metres of Plot elm hedges. Tree populations have further been reduced by road widening and by removal of hedgerows.
Though Plot elm is nationally scarce, it is not considered critically endangered. Young trees grow as suckers from the roots in hedgerows but in all known locations rarely reach more than 6 metres high until succumbing to disease with young suckers then taking their place.
Credit: Clive Stace
The Plot elm is generally considered a tree of the East Midlands, though credible records also exist of populations surrounding Cirencester and Shrewsbury.
Though Plot elm is not available commercially, hybrid cultivars are available, the most well know of which are: Ulmus × hollandica 'Jacqueline Hillier' (available from many UK nurseries) and Ulmus × viminalis 'Aurea' (available from a nursery in Poland).