The firm was originally started by Henry Stothert in 1837 as Henry Stothert and Company.
The company was given an order for two broad gauge 2-2-2 Firefly class express passenger engines which were delivered for the opening of the Great Western Railway (GWR) from Bristol to Bath on 31 August 1840. This was soon followed by an order for eight smaller 2-2-2 Sun class engines.
Edward Slaughter joined the company in 1841, when it became known as Stothert, Slaughter and Company. By 1844 their works were named Avonside Ironworks.
In 1846 the firm built the first of five six-coupled saddle tank banking engines for the GWR. Another large order came for ten broad gauge passenger 4-2-2s and eight goods engines from the Bristol and Exeter Railway for the independent operation of that line from 1 May 1849. In 1851 the company acquired a shipbuilding yard, of which Henry Stothert took charge as a separate undertaking.
In 1856 Henry Grüning became a partner of Edward Slaughter at the locomotive works, which then became Slaughter, Grüning and Company.
The Avonside Engine Company was formed in 1864 from the business of Slaughter, Gruning & Co. with Edward Slaughter in control.
The works received a large order (the first from the GWR for some years following the development of the Swindon Works) for twenty 2-4-0 engines.
During the 1860’s and 70’s the Avonside company built broad gauge and standard gauge engines for a many British companies, large and small but they also built up a considerable export business.
1871 Avonside Engine Co took over the rights to the Fairlie designs from Fairlie Engine and Steam Carriage Co.
1872 Amongst the first to be built at Bristol was James Spooner built in 1872 for the Ffestiniog Railway. Although built to the same basic design as the successful Little Wonder built by George England in 1869, it incorporated many detailed improvements and became the prototype for subsequent Ffestiniog Railway engines built in that company’s works at Boston Lodge.
1874 Edward Slaughter retired from his post as Managing Director due to ill health
1875 the company built four powerful tank engines designed by a Swedish Engineer, H. W. Widmark, to operate on the Fell mountain railway system on the Rimutaka Incline in the North Island of New Zealand. One locomotive is preserved at the Fell Locomotive Museum, Featherston, New Zealand. These and two later engines of very similar design built by Neilson and Co handled the entire traffic for eighty years until the opening of the five mile long base tunnel in 1955.
1878/79 on the recommendation of Robert Francis Fairlie Avonside built a class of 21 0-6-4 single Fairlies for the New Zealand Government Railways.
By 1880 around 450 people were employed at the works in Bristol building locomotives for use on the main lines of Britain as well as for overseas companies.
The Avonside Engine Company and its predecessors were unusual in that most of the production before 1880 consisted of main line locomotives largely for British railway companies but also for export. However, by 1881 main line locomotives were getting much bigger and exceeding the capacity of the manufacturing equipment. They made a positive decision to concentrate on the smaller Industrial railway locomotive types for within the capacity of the existing plant. This change was to a degree forced on the company as a result of financial difficulties following Edward Slaughter’s death. Edwin Walker of the Bristol Engineering firm Fox, Walker & Co. joined Avonside and endeavoured to turn the company round, but without success.
1881-2 The company went into liquidation during a recession in the industry, despite a late surge in export orders. The site was sold to paper maker John Mardon (becoming Avonside Paper Mills, later owned by Smith, Stone and Knight).
1882 the northern part of the site was leased to Edwin Walker, of Bristol locomotive manufacturers Fox, Walker and Co, who also bought the machinery, patterns and spares.
By this time main line locomotives were getting much bigger and exceeding the capacity of the manufacturing equipment. They made a positive decision to concentrate on the smaller locomotive types within the capacity of the existing plant.
Edwin Walker endeavoured to turn the company round, but without success. He was forced to liquidate the old company and form a new company with the same name to carry on the same business at the same address.
Over the years, the works had expanded, but latterly the business retrenched to occupy just the northern part of the of the site. Avonside and Mardon’s were joined by a third company, Owen, Brazil and Co., who named their building the Vulcan Iron Works.
In 1905 the Avonside firm left its historic home at St. Philip’s for a new plant at Fillwood Road, Fishponds but still with a small engine policy.
1934 The company closed and the goodwill and designs of the company were bought by the Hunslet Engine Co.
Preserved Locomotives
I have only included standard gauge locomotives which are preserved in Britain.
For Andrew Barclay built locomotives preserved outside Britain go to Preserved Outside Britain by Builder – Avonside
There is one preserved locomotive built by the Avonside Engine Company for the Londonderry Port and Harbour Commissioners – Works No 2021.
| Works No | Built | Name/Number | Type | Location |
| 1386 | 1897 | GWR 1340 Trojan | 0-4-0ST | Didcot Railway Centre |
| 1421 | 1900 | No2 Pontyberem | 0-6-0ST | Pontypool & Blaenavon Railway |
| 1465 | 1904 | MD & HB No1 | 0-6-0ST | National Museums Liverpool, Vehicle Workshop |
| 1498 | 1906 | Desmond | 0-4-0ST | Llangollen Railway |
| 1563 | 1908 | Millom | 0-4-0ST | Foxfield Railway |
| 1568 | 1909 | Lucy | 0-6-0ST | Ribble Steam Railway |
| 1572 | 1910 | Woolmer WD 74 | 0-6-0ST | Milestones Living History Museum |
| 1600 | 1912 | 0-6-0ST | Bryan Engineering Services, Bolton | |
| 1680 | 1914 | Sir John | 0-6-0ST | Pontypool & Blaenavon Railway |
| 1764 | 1917 | 34 Portbury | 0-6-0ST | Bristol Harbour Railway |
| 1772 | 1917 | Askham Hall | 0-4-0ST | Threlkeld Mining Museum |
| 1798 | 1918 | Edwin Hulse | 0-6-0ST | Avon Valley Railway |
| 1810 | 1918 | MD & HB 26 | 0-6-0ST | Ribble Steam Railway |
| 1865 | 1922 | Elizabeth | 0-4-0ST | Rippingdale Station, Lincolnshire |
| 1875 | 1921 | Barrington | 0-4-0ST | Colne Valley Railway |
| 1883 | 1922 | Joan | 0-6-0ST | Ribble Steam Railway |
| 1917 | 1923 | Earl Fitzwilliam | 0-6-0ST | Elsecar Heritage Railway |
| 1919 | 1924 | Cranford | 0-6-0ST | Appleby Frodingham Railway Preservation Society |
| 1971 | 1927 | Sir Thomas | 0-6-0ST | Dover Transport Museum |
| 1972 | 1927 | Stamford | 0-6-0ST | Rocks by Rail |
| 1973 | 1927 | RRM 3 Dora | 0-4-0ST | Rippingdale Station, Lincolnshire |
| 1977 | 1925 | Cadbury No1 | 0-4-0T | Tyseley Locomotive Works |
| 2004 | 1927 | St Dunstan | 0-6-0ST | East Kent Light Railway |
| 2068 | 1933 | Robert | 0-6-0ST | Stratford station forecourt |
Preserved British Steam Locomotives 