This looks like a really exciting event!
What could be more iconic of the British Empire than the red pillar box emblazoned with the monogram of the monarch? Both South Africa and the Irish Republic kept their pillar boxes after independence but the Irish ones were promptly repainted in green, while the remaining South African ones are still red. Meanwhile in both countries they provide a space for displaying official language policy. The South African one (photographed in 2012, but probably unchanged for at least 20 years) reflects the Apartheid-era policy of treating English and Afrikaans as equal official languages in accordance with the 1910 constitution, but ignoring the rest (there are now 11 official languages under the 1996 constitution). The Irish pillar box (photographed in 2006) shows English (the second official language according to the constitution of the Republic) and Irish (the ‘national language and first official language’), in that order (i.e. the second official language first). In both the South African and cases, exactly the same content is given in both official languages and the fonts and letter sizes are identical for both, metaphorically establishing the languages as equally important.
Despite the South African constitution declaring 11 languages now to be official, the most recent incarnation of the posting box is just in one language – English. the same, incidentally, is true of the stamps.