On 31 December 1868, Szlumper was appointed Chief Engineer of the Whitland & Taf Vale Railway (W&TVR), having been recommended by business partner and Member of Parliament David Davies. The W&TVR was closely aligned to the Pembroke and Tenby Railway (P&TR), having a virtually common set of investors and board of directors. The P&TR also had close links to the Manchester and Milford Railway (M&MR), which ran over the Szlumper engineered metals of the Carmarthen and Cardigan Railway (C&CR) to connect to Carmarthen station