Quote:
There is a perfectly good route number for the 46A already - 46A
You'll have to forgive my personal sensibilities, but it is an alpha-suffixed route with no equivalent un-affixed route number associated with it (the 46, as an infrequent route that did not provide parallel service to Dun Laoighaire, wasn't "equivalent" so to speak, as the 40 and the 40A for example).

People took it well when the 50A to Jobstown became the 50; same when the 38A and 38C were consolidated into the 38.
Quote:
Why change what is probably the best known route number in the whole city, one so embedded in popular culture that it is actually immortalised in song?
Better known than the 10?

To be honest, when I think of buses bound for Dun Laoghaire, the 7 and 8 spring more readily to mind (and the 8 nowadays avoids DL).

And from old destination signs, I used to think of that bus as the A46 (alpha-prefixed), which wouldn't be so bad if the alpha-prefix were indicative of a certain area of coverage (like the alpha prefixes on New York City buses, so assigned by borough, e.g. M for Manhattan, B for Brooklyn, et al).

Pity Bagatelle isn't well-known on the other side of the Atlantic. When you say "Irish band", first thing out of people's mouths in the US is "U2"...