The Stamp on the Road

As I was walking last July.
Not far from my august abode,
My eagle eyeballs chanced to spy
A square of paper ‘pon the road.

‘Twas lying there, upon that road
Upon the apex of a ramp.
Instinctively, therefore, I slowed
And saw it was a postage stamp.

I craned my head to better see
This postage stamp upon the road.
It was an old one, priced 4p,
That advertised the Green Cross Code.

I reminisced beside that road
And heard again that old refrain
That sweeping time can ne’er erode –
“Look left, look right, look left again.”

A thirty year old postage stamp
Depicting what? The Green Cross Code?
Why was it lying ‘pon a ramp
Not far from my august abode?

I moved to step onto that road,
As most philatelists would do,
But I forgot my Green Cross Code
And never saw the Subaru.
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Homework from the Phoenix Writers Club - do something with a theme of "The Stamp" or "The Road."