Could this be your Edgar in 1901? Not born Pontypridd but Porth isn't so far away.
RG13/5001/161/26 Ystraddfodwg and Llanwonno
16, North Road
George Rossiter, 36, Colliery Repairer, Somerset Evercreech
MariaAnna, 35 "
Edgar, 5 Glamorgan, Porth
Madge, 4 "
Hester Trim, 14,niece, "
William March, 35, Lodger, Somerset, Evercreech
Blanch Rosseter, 3, Porth
Rosa, 1 "
Not sure why the niece and lodger come between the offspring but that's the way it is entered.
Hope it is helpful,
Jen
