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Wren & Hopkinson of London Road Ironworks, Altrincham Street, Manchester. The address also appears as Temple Street, Manchester. The works was evidently at the junction of these two streets, on the west side of Temple Street. The area has now been completely redeveloped.
Formerly Wren and Bennett, and then Wren, Wren & Hopkinson
Maker of stationary engines. 
Other products included textile machinery, gears for mills and steamships, waterwheels, hydraulic presses & pumps.
1855 'THE FLOATING BATTERIES FOR THE BALTIC. - It may be interesting to our readers to know that some portion of the machinery for the floating batteries preparing for the Baltic, has been constructed in Manchester during the last few days. The batteries are vessels of great tonnage, built very square, each 50 feet breadth of beam, 7 feet draught of water, and are pierced on each side for 16 guns, the armament being 16 68-pounders ; so that the whole of the guns can be used on either one side or the other. The sides are cased two feet below the water line with solid wrought iron plates four inches thick. They were originally intended to be propelled by one screw of six feet diameter, but when almost ready for launching, it was considered that a single screw would not afford sufficient surface to act against the water for the propulsion of vessels of such large tonnage and of necessarily unfavourable lines, and it was determined to furnish each vessel with three screws, each six feet diameter, as no larger could be obtained with so small a draught of water. The two secondary screws are fixed upon shafts parallel to the main shaft, which runs as usual in the centre of the vessel, from the engines to the stern; motion being given from it by an iron spur-wheel, working into a wheel with wood cogs on each secondary shaft. The arrangements for connecting are so made that any one, any two, or all three screw propellers may be in work at one time, with the obvious advantage that if one or two of the propellers become injured or thrown out of use by shot or otherwise, the remaining one is still available. This additional means of propulsion having been decided on at the last moment, the utmost expedition was needful to prevent delay in the launching of the vessels, and Messrs. Miller, Ravenhill, and Salkeld, of London, were commissioned to effect the change in three of the five batteries. They directed their energies to the preparation of the needful shafts, screws, and fixings connected with them, and entrusted the construction of the toothed gearing to Messrs Wren, Wren, and Hopkinson, millwrights, of this city. The order was received on Good Friday, and by some exertion the nine large wheels required were completed in ten days; the last having been forwarded to London on Tuesday last.' 
Note: The gears were for the Aetna Class Ironclad Floating Batteries
John Dewhurst's Belle Vue Mills in Skipton designed by Wren & Hopkinson 
c.1862 Appointed manufacturers for F. O. Ward's hydraulic pumping engine, for printing presses and other purposes
1867 At The French Exhibition: 'Messrs. Wren and Hopkinson exhibit much valuable machinery— compound oscillating engines, travelling cranes, Mohler's patent for lubricating axles and shaft journals, Smith's doubling and winding frame, and and Smith's spooling machine, which is creating a sensation, and taking extensive demands from French spinners.'
1880 Supplied overhead cranes (rope-driven) for Joseph Whitworth & Company’s new Openshaw works.
About 1880 Mr. Hopkinson withdrew from the firm
THE FATAL CRANE ACCIDENT IN MANCHESTER. The City Coroner (Mr. E. Harford) held an inquest to-day touching the death of Edmund Matthews, aged 19, a labourer, late of Ogden-street, Ardwick, who died from the injuries received by the fall of the travelling-crane on which he was working. Thomas West, foreman at Messrs. Wren and Hopkinson's, engineers, said that the crane was being yesterday morning employed for the purpose of lifting a cylinder, weighing about nine tons, and conveying it from one part of the yard to its bed. The crane was an ordinary travelling crane, running upon a railway fixed on two long beams, which were supported by uprights. The deceased and five other men were engaged on the crane lifting the cylinder, and having raised it about a foot, they set the crane in motion along the rails, but just as if had passed one of the uprights, the beam on which the rail is supported smashed, and the whole of the crane, together with the cylinder, fell to the ground, the deceased being crushed between the cylinder and one of the uprights. He was taken to the Infirmary, whore he died last night. The crane was not constructed to carry heavier weights than ten tons. The rail was supported on two beams which were joined close where the breakage occurred, and it was the giving way of the end of one of these beams which caused the accident. The beams had been examined a few days before for the purpose of ascertaining their condition. The structure had been erected about 12 years. Daniel Hysslop, a joiner, in the employ of Messrs. Wren and Hopkinson, said that he had examined the beams a few days previously and found them apparently quite secure and sound.
Mr G. H. Goldsmith, architect, said that he had examined the remains of the beam which had given examined the remains which had given way. It was apparently quite sound when examined outwardly, but the whole interior near the fracture was decayed and rotten to such an extent as to crumble in pieces when shaken. This had been caused by the entry of water at the junction of that beam with the other, and the broken beam had in its descent dragged the other one with it. The man who had examined the beams just before could have detected rottenness by pushing any instrument into the beam, but when struck, or otherwise tested, the fault could not be detected. All cranes of that kind were liable to the same thing, particularly at the junctions of the transverse beams.
Mr J. Hopkinson said that the crane had been put up by the firm about twelve years ago, under the direction of an experienced carpenter. The timbers were then quite new and sound. It had not occurred to him (Mr Hopkinson) that the end of that particular beam would rot as it had done, considering that the whole of the beam was equally exposed to the weather, the end of the beam was more liable to rot than the centre, because the rain made an entrance at the junction of the beam with another The whole structure should be pulled down, and a new one built, so as to prevent the ocurrence of such accidents in future. The jury returned a verdict of accidental death.