>I think that Northern Ireland will not change to >metric on the roads when Ireland does so.
You think correctly. >Here and thee I have seen metric head room signs, together >with foot-inch ones. The metric values are neat hard metric >like: 12" on the imperial, 3.60 m on the metric sign. Your experience would be the same in the rest of the UK. Headroom signs are generally not government installed and are interesting for the following reason: They may indicate how private businesses think they should communicate official messages.
