The comments pointed me to an answer to my own question (ta!).

Exceptions to the doubling rules are discussed in Double Consonants in Gerund .

Relevant here is the rule:

Two-syllable words: ED = If the stress is on the first syllable, the word only gets one consonant + ED.

(from http://a4esl.org/q/h/9807/km-doubles.html)

In British English the stress is on the first sylable of detail, [ˈdi(ː)teɪɫ] (source wictionary).

As an amusing aside, in American, the stress is apparently on the second sylable: If consonants were doubled in American English, it would be detailled in the US and detailed in the UK, wouldn't it?

Please note: While writing this I have been informed by Araucaria that these rules would not apply to this problem. Please consider above in the light of that comment.

The comments pointed me to an answer to my own question (ta!).

Exceptions to the doubling rules are discussed in Double Consonants in Gerund .

Relevant here is the rule:

Two-syllable words: ED = If the stress is on the first syllable, the word only gets one consonant + ED.

(from http://a4esl.org/q/h/9807/km-doubles.html)

In British English the stress is on the first sylable of detail, [ˈdi(ː)teɪɫ] (source wictionary).

As an amusing aside, in American, the stress is apparently on the second sylable: If consonants were doubled in American English, it would be detailled in the US and detailed in the UK, wouldn't it?

Please note: While writing this I have been informed by Araucaria that these rules would not apply to this problem. Please consider above in the light of that comment.

The comments pointed me to an answer to my own question (ta!).

Exceptions to the doubling rules are discussed in Double Consonants in Gerund .

Relevant here is the rule:

Two-syllable words: ED = If the stress is on the first syllable, the word only gets one consonant + ED.

(from http://a4esl.org/q/h/9807/km-doubles.html)

In British English the stress is on the first sylable of detail, [ˈdi(ː)teɪɫ] (source wictionary).

As an amusing aside, in American, the stress is apparently on the second sylable: If consonants were doubled in American English, it would be detailled in the US and detailed in the UK, wouldn't it?

The comments pointed me to an answer to my own question (ta!).

Exceptions to the doubling rules are discussed in Double Consonants in Gerund .

Relevant here is the rule:

Two-syllable words: ED = If the stress is on the first syllable, the word only gets one consonant + ED.

(from http://a4esl.org/q/h/9807/km-doubles.html)

In British English the stress is on the first sylable of detail, [ˈdi(ː)teɪɫ] (source wictionary).

As an amusing aside, in American, the stress is apparently on the second sylable: If consonants were doubled in American English, it would be detailled in the US and detailed in the UK, wouldn't it?

Please note: While writing this I have been informed by Araucaria that these rules would not apply to this problem. Please consider above in the light of that comment.