Even when I wrote the word in the headline and in this post, it was underlined to alert me to the misspelling, but in England, it's okay. And after doing a search online, I noticed that it's the correct spelling in Canada, too. A CTV news story from today says, "he advised that dialling 911 is still the best option during an emergency." There goes that spell-check warning again because I'm in the USA, and here we write "dialing," which seems to make more sense to me.
I know that the English-speaking world has different spellings for different words (such as "specialize" and other words that end in "lize" in American English, but "lise" in other countries). I also know that American English is not the mother tongue, so what right do we have to question anything? But still, after a lifetime of seeing a single "l" after "dial," it's jarring to see two of them.
This England-dwelling American says the double-l doesn't make sense linguistically.
Ones that really strike my American eye as wrong are BrE dialling and fuelling. Since the l is preceded by a 'long' vowel (the diphthongs /aj/ and /ju/) in my pronunciation), they shouldn't have doubled consonants, just as one doesn't double the L in tailing or healing. They seem to come under the 'doubling' rule because dial and fuel are perceived as having two syllables each, with the latter one being unstressed--i.e. di-al and fu-el. The COD presents the BrE pronunciation as /dai(ə)l/ and /'fju:əl/--so definitely two syllables in fuel but not necessarily in dial.
Actually, I think I usually pronounce "dial" as two syllables, but since the emphasis is on the first syllable, the "l" still "shouldn't" be doubled. (I put "shouldn't" in quotes because it seems to be some old rule, and who am I to judge?) I don't have any linguistic theory to add, so I'll just simply say that the spelling seems weird (that's my non-intellectual, non-academic take on it, since I don't even claim to be a linguist).