An historic moment

The indefinite article of English is either <a> or <an> depending on whether the following word starts with a consonant or a vowel sound - so far so regular. But what do we make of book titles such as these?
How do you pronounce the phrase "an historical" or "an historic"? Should it be /ən ɪstɒrɪk(əl)/ or /ə hɪstɒrɪk(əl)/? Could one also say /ən hɪstɒrɪk(əl)/?
Well, Alex Rotatori has spotted an interesting spoken example of the latter version (though the indefinite article is used here in its strongform /æn/); it's taken from Theresa May's speech in the House of Commons announcing the delivery of the Brexit letter to His Excellency Mr Donald Tusk, president of the EU.

Is it something which occurs occasionally, even regularly, is it idiosyncratic or just a slip of the tongue/brain?

Seven Sisters

"Seven Sisters Station" is an underground and overground station in an area of North London called  "Seven Sisters". This strange name seems to go back to seven elm trees that had been planted there in the 17th c.,

before they were finally replaced by a ring of hornbeam trees at the end of the 20th c., though not exactly at the same place.
The Independent published this photo of seven nuns making for an amusing appearance while they were waiting at Seven Sisters station.

credit: The Independent

PS: Should you be a lady heading for Cockfosters, a London suburb, and are unsure whether you are on the correct line, never ask the gentleman next to you: "Is this Cockfosters?" You might get an unexpected answer.
PPS: Others spring to mind: Bakerloo, Barking, Elephant and Castle, ... 

An old dictionary

It was by mere chance that I stumbled across an eighteenth-century dictionary indicating stress though not pronunciation:
Thomas Dyche (1740³), A new general English dictionary, (London). It's to be found at www.archive.org. Here's the title page of the 3rd edition:

Thomas Dyche

Next a sample page, which shows, among other words, the stress pattern for forthcoming.

 The final 20 or so pages contain a list of names of persons and places with their stress patterns. This list ranges from Aaron and Abaddon over Monserrat and Montanus to Zygaces and Zygantes.

We don't know much about Dyche; there is, however,  an interesting article on Dyche (and his co-author Pardon) written by D.T. Starnes and G.E. Noyes: "Thomas Dyche and William Pardon's A New English Dictionary (1735)" to be found in R.R.K. Hartmann, ed. (2003), Lexicography, vol. 2, pp. 15-28 (London, New York).