As virtually always, things are not quite that simple. The metric system was rationalised by British Association for the Advancement of Science based on c.g.s (centimetre, gram and second) units in 1874. The Italians produced another rationalised system based on MKS (metre, Kilogram and second) in 1901. Both systems were in use until 1960 when the International Committee for Wieghts and Measures (CIPM after the French translation) developed the International System (SI, French again) out of the MKS. To bring things up to date, the International System of Quantities (ISQ) is based on the SI system and is defined in ISO 80000.
On the continent they have long been used to the cgs system and don't see why they should change to new-fangled units, and so retain the use of the centimetre. In the UK we are transitioning to ISQ approved SI, and so we eschew the cm as old-fashioned and non-standard.
You're quite right about familiarity. There are plenty of other instances of established standard being forced into metric, or else simple accepted.
Two small points. (1) A small typo: 2440mm = 244cm = 2.44m.
(2) The standard abbreviation for an old penny was "d", not "p", so your prices should have been 1s 10d and 2s 11d, or as more commonly written 1/10 and 2/11. I too learnt to do my arithmetic whilst the beer flowed. If you were having problems you just pulled the handle more slowly!