But I would walk five hundred milesThe ambiguity is not merely textual but is produced by the interaction of the lyric and The Proclaimer twins' alternate delivery of the first two lines of the chorus (the remaining two lines are delivered jointly). One twin is proposing to walk 500 miles and the other is, seemingly, proposing to match (or possibly even double) his brother's prodigious perambulatory feat. The song, therefore, implies not only that both twins arrive at the destination but also that the walking and, more worryingly, the romancing are shared, rather than individual, endeavours. We must logically conclude that the "man" (rather than "men") who collapses at the door is the Proclaimers' "unified fraternal persona."
and I would walk five hundred more
just to be the man who walked a thousand miles
to fall down at your door
The issue is further complicated by each twin's assertion that they will have walked one thousand miles when, it seems, they're planning on sharing the task and only traversing 500 miles each ~ unless the latter Proclaimer twin is proposing to eclipse the former by walking 1000 miles (his 1000 being 500 "more" than his brother ~ in which case we presume he's proposing to start 500 miles behind his brother and to accompany him for the final 500 miles ~ and, thus, amounting to a joint 1500) by contrast with the more conventional interpretation, which suggests that the 500 "more" than his brother's 500 is also 500 (thus totalling a mere 1000 miles between them). Either way, at least one of the twins' "1000 mile" claim is bullshit.
At it's irreducable minimum the song seems to be describing a romantic triangle, yet it's unclear whether the object of the Proclaimer twins' affections is likely to a) expect some kind of crass Darwinian "survival of the fittest" showdown between her (or his) prospective suitors or b) consent to a request for a ménage à trois. The possibilities that the Proclaimers might be required to c) form (or join) a queue or , perish the thought, d) meet with rejection at the end of their journey cannot be discounted ab initio, and textual interpretation alone fails to elucidate the conundrum.
Ashley Pomeroy's analysis (see link) is rigorous but hardly exhaustive: he doesn't consider, for instance, the possibility that the object of the Proclaimers' romantic yearnings may be, in turn, a unified persona comprising seperate constituent personae. If this is indeed the case then the carnal possibilities expand exponentially.
One thing is certain though: any, and all, proposed amorous activity is likely to postponed until the conclusion of a prolonged recovery period after such a gargantuan trek. The Proclaimers' prospective paramour(s) would be well advised to stock up on fluids, high-glycemic/carbo-loaded foodstuffs, warm blankets and saline drips in anticipation of the pair's arrival.
Pomeroy analyses the mathematical conundrums inherent in the lyric and considers a few of the myriad romantic permutations generated by this polymorphously perverse Pandora's Box of Amorous Possibility.
With regard to the plethora of non-traditional romantic combinations implied by the lyric: Pomeroy, tentatively, concludes that close textual analysis favours a "brotherly love" interpretation over the "group sex" hypothesis. Whether his conclusion is warranted is open to debate.
Ashley Pomeroy's thoughts on 500 Miles