Sparrows nesting on the house walls

When we first moved here we had two or three Sparrow nests 'in' the roof space or at least on top of the thick walls accessed where there was a suitable opening under the soffit boards. Then about three years ago the Sparrows just disappeared and we rarely even saw one flying about the place. One pair came back two years ago and nested in a House Martin next cup I had put up under the eaves at the side of the house and that cup was again used last year. This year the Sparrows seem to be back in greater numbers and we have once again a pair nesting in one of the old nest sites just under our roof. I also saw one flying from a nest box we have on the other side of the house. I only wish the Swallows would come back and next in our barn as they used to.