I had the same problem with the currency.
7 shillings, 6 pence is consistent with Australian currency in 1964 (12 pence to the shilling).
However, in East Africa they were using shillings divided into 100 cents.
Also, in Australia, a first world country, paying 7s, 6p was not an unreasonable amount to pay for a certified birth registration.
But in Kenya, a third world country with millions and millions of people living at subsistence level, 7s, 6p (setting aside the incorrect currency designation) would have been an ENORMOUS amount for the average Kenyan to pay for a birth certificate. Now having said that, it may have been that most Kenyans did not bother, or were not in a position, to have their births registered, but still, for those who did, that would have been extremely expensive.
I hadn’t thought to check the comparative value. Excellent point.