It was the third railway company in Ireland to operate passenger trains and the first to use the Irish standard 5 ft 3 in (1,600 mm) gauge.

The opening of the Dublin and Belfast Junction Railway (D&BJct) between the D&D at Drogheda and the Ulster Railway (UR) at Portadown in 1852 saw an almost continuous main line connection between Dublin and Belfast, which was resolved by the official opening of the Boyne Viaduct in April 1855.

An amended bill presented to Parliament in February 1840 and assisted by the services of Daniel O'Connell and eventually passed as the Dublin and Drogheda Railway Act 1840 (3 & 4 Vict.

The line was proposed to be built to 5 ft 2 in (1,575 mm) gauge[3] on the grounds of lower costs.

Following complaints from the UR the Board of Trade investigated the matter, and in 1843 decreed the use of 5 ft 3 in (1,600 mm).

[4] On 20 May 1844 Major General C. W. Pasley, the Inspector General of Railways inspected the D&D slowly in one direction and with a reverse run at speed highly commended the works and recommended to the Board of Trade they permit the line to be opened on 24 May 1844.

The following stations were served by the line when it opened: Royal Canal (Temporary Dublin terminus - replaced by Amiens Street Station on 29 November 1844); Clontarf; Raheny; Baldoyle; Portmarnock; Malahide; Donabate; Rush and Lusk; Skerries; Balbriggan; Gormanston; Laytown; Bettystown; Drogheda.

[citation needed] The line became operationally complete when the first train crossed the Boyne Viaduct on 5 April 1855.

[16] Grendons had built some small 2-2-2 locomotives that were later to converted to tank engines notably without brakes.