The UK switched to metric in 1965 and by the end of the 1970's most industries had fully switched. The UK is now officially a metric country, engineering and regulation are fully metric.
I have read an article on the internet (Cannot remember the link any more) which compared Canada and UK's metrification. It observed that Whilst Canada superficially presents itself as more metric country, it is still very much internally imperial, with a lot of engineering, and process still calculated in imperial units. Even in many cases food is sold in imperial. This may be due to the US influence there, but its very apparent when you go there.
The UK on the other hand appears superficially Imperial (distances, milk, draught beer, etc), and with some curious mixes, such as temperature, where media sometimes report how "hot" the wether is is presented in imperial F, whilst when reporting how cold the weather is, its reported in C. However, internally we are almost fully metric, with house/road building done in metric, even the motorway markers on the side of the motorway are actually in KM, not miles (as mentioned briefly above). Have a look next time you are on the motoway.
To be honest, I think this is very much a common sense approch to all this. Imperial units are mainly advantages in relative calulations (Jerermy Clarkson once explain in his satrical way how an american builder than build a roof based on how many "lengths" of 2x4 timber beams, without cranking out hte calculator). Metric is vital any abolute and arbitrary calculations and especially non relative calculations, where imperial calculations will be more difficult, and error prone.
I think one notable exception, to metrification is angle mesurement, although a metric unit does exist (Gradians or gon - 0 -400) computers still use Radians (a unit based on PI, where 360 degrees = 2PI) due to beign easier to work with, especially as most angle calculatiosn are relative.
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