Conventional wisdom has it that the heartlands of rugby in Britain are somewhere in the West Country or the valleys of Wales.

Cup winners: Lawrence Okoye, one of the stars of Whitgift's national title-winning side last season

But what this Saturday will demonstrate again is that Croydon ought to be looked upon as the centre of real rugby excellence, as Whitgift School take on John Fisher in their annual, bruising encounter.

Officially it is a “friendly” fixture, but this is a derby match as fiercely fought as anything between Gloucester and Bath, or even Arsenal and Chelsea.

With staff, parents, boys from games played earlier in the day, the fixture has an estimated crowd of more than 2,000, all standing three or four deep around the pitch for the ultimate contest, between the schools’ first XVs.

The excellence of the two schools’ high-profile rugby “programmes” is demonstrated by their performances in the Daily Mail Cup, the national schools’ competition, in the past couple of years.

In 2009, Fisher were incredibly unlucky to be knocked out on penalty kicks at the semi-final stage. Last season, Fisher might have progressed to the final at Twickenham had they not been unfortunate to meet the eventual winners in an early round. Their conquerors then were Whitgift.

Fisher pride: Paul Sackey on England duty

The South Croydon independent school ultimately won the final at Twickenham in April against opposition from Newcastle Grammar. The last time Whitgift took a Daily Mail Cup was at the beginning of the decade when they won the under-15s trophy with a side that included a certain Danny Cipriani.

Fisher, a state church school, has turned out its fair share of senior England internationals, too, with Wasps wing Paul Sackey being their most prominent discovery so far. Their current side includes the England under-16s capped Ben Axten-Burrett.

Both schools take their rugby as seriously as the sort of thing normally offered by American high schools for basketball and grid iron.

Through talent identification, coaching and some assiduous recruitment, Whitgift’s current first XV included the likes of Eliot Daly, an England under-16 international at rugby and cricket, George Merrick, the England under-18s lock forward nicknamed “The Fridge” (you’ll know why when you see him), and classy flanker Harry Ledger.

But the Whitgift side that managed to beat fierce rivals Wellington College 8-0 last Saturday also included homegrown players like Stacey Wright, who has been at the school from the age of 11. The son of former Palace, Arsenal and England footballer Ian Wright and brother of Shaun Wright-Phillips, Stacey Wright plays his part in the Whitgift rugby side as a hefty prop forward.

The Whitgift v Fisher rugby day kicks off this Saturday, October 9, at 10.30am, with matches split between Whitgift School in South Croydon and John Fisher’s playing fields on Plough Lane, Purley.

Any politicians who still claim there is no competitive sport played in schools would do well to pay a visit, as the schools manage to turn out at least two sides in each of six age groups, all staffed and properly refereed, with the respective PTAs laying on teas and refreshments.

This year’s senior games, with 2nd and 3rd XV matches staged just before the 1st XV showdown at 2pm, will be at Whitgift.

And there will be more than a bit of pride to play for: the last team to beat Whitgift before they went on to their Twickenham triumph was Fisher in the corresponding fixture 12 months ago.