Melt 1½ ozs. of butter in a saucepan, add the vegetables cut in small dice, also the ham. Simmer very gently for 15 minutes, but without browning in the slightest. Now put the vegetables on a plate, and in the same saucepan blend the other 1½ ozs. of butter with the flqur to a smooth paste. Add the hot milk very gradually, stirring continually. Replace the vegetables in the sauce, with the herbs, season with salt and pepper, and simmer for ¾ of an hour. Strain, and use as required.