I know of no Verbena with anything other than basically green leaves - shorter versions of Verbena bonariensis don't exist, but there a couple similar in habit that don't get so tall - Verbena hastata and V. corymbosa.

Thanks for that, there is a short version of bonariensis called lollipop which has green leaves but this one I have now has the normal shape leaf for a bonariensis but is of this extraordinary colour.

If the plant has been in a sheltered spot and has kept its leaves, many plants react to colder temperatures by leaves turning tones of red/purple. Verbena are usually herbaceous perennials, mostly disappearing in winter apart from dead looking stems, but its possible its hung onto its leaves and that's why they're this colour. You'll know as it grows again this year what colour the leaves are for sure.

Have found out what it is! Verbena officinalis grandiflora "Bampton",thanks for your help.

Thanks for letting me know - I don't know this plant, never seen it. I like the colour of the leaves, but its growth habit appears to be not only lower, but more sprawly. Listed as a rockery plant on some sites. Nice though.