Having received a thrashing, it is human nature to examine the events which lead up to the debacle, and to then to assign blame. The South African farmer was a fine shot (after shooting with a couple of them I suggest they still are) having grown up shooting game where as the typical British soldier learned marksmanship on the rifle range and from reading Kipling . . .
When 'arf of your bullets fly wide in the ditch,
Don't call your Martini a cross-eyed old #####;
She's human as you are -- you treat her as sich,
An' she'll fight for the young British soldier.
Fight, fight, fight for the soldier . . .
The British Army has fielded some fine marksmen, but there is nothing in the English countryside that promoted a gun culture as it had developed in what is now the RSA. Nevertheless, the Brits are very good at doing whatever is necessary to win wars, and such was the case with the Boers.