 He supervised estates in the West Midlands and beyond for, amongst others, the Dewes family of Wellesbourne Hall, Warwickshire; the Earl of Warwick, of Warwick Castle (but with property widely distributed); the Yates family of Lancashire; the Earl of Dartmouth at Sandwell Park, West Bromwich; the Archbishop of Canterbury at Lambeth in London; and the Agar family of Lanhydrock House in Cornwall.James sought unsuccessfully for coal in East Sussex but successfully operated coal mines in his own right in south Staffordshire.Having an understanding of geology, James invariably advised his clients to concentrate on realising the mineral wealth of their estates and it was in this connection that he first began to propose railways, including, in 1802/03, an early version of the Bolton and Leigh Railway.