12 Sentinel 0-4-T Sentinel Works No 6515

Introduced	1926
Designer
Company	GWR
Weight	20t 17cwt
Driving Wheels	2ft 6in
Boiler Pressure	275psi
Cylinders	6.75in x 9in
Tractive Effort	19,870lbf
Valve Gear	Stephenson (slide valve)

This Sentinel engine is similar to the LNER Y1 class introduced in 1925. It has a direct chain drive between crankshaft and axles.

It was delivered new to GWR for trials and taken into stock as number 12 in 1926. It was fitted with equipment for working train vacuum brakes and steam heating, and was based at Swindon for use on the Malmesbury branch before being sent to work at Brentford Goods Yard. It did not prove to be a successful working engine and was taken out of service in 1926 and returned to Sentinel.

Modifications were carried out in 1927, including the fitting of a larger boiler, which enabled further trials, including passenger working, to take place on the Shropshire & Montgomeryshire Railway during the latter part of that year. The locomotive then returned to the GWR where more trials were undertaken on the Malmesbury branch towards the end of 1927. During these trials a speed of 38mph was attained, hauling a train of three four-wheel coaches, taking just 16.5 minutes to cover the 6.5 miles from Malmesbury to Dauntsey. After this the locomotive returned to Shrewsbury, where it was used by Sentinel as a works shunter until 1929, when once more it underwent trials, this time on the LMS at Shrewsbury. More works shunting followed until it was sold in October 1934 to Thomas E. Grey Ltd. of Burton Latimer, Northamptonshire, where it was numbered 2 and carried the name Isebrook. It worked until 1958 when a more modern Sentinel replacement.

The boiler and parts of the engine were removed and it was used as a brake van until condemned in 1972, shortly afterwards being purchased for preservation and moved to Quainton on 31st May 1972. Restoration work took seven years and included fitting a reconditioned boiler and engine unit, extensive bodywork replacement as well as a complete renewal of pipework. The first steaming for over twenty years took place on 26 August 1979. The locomotive was restored to lined black livery. During 1981 vacuum brake equipment was refitted enabling light passenger trains to be worked.

Isebrook left Quainton on 31st May 2001 for Rosemary Vineyards on the Isle of Wight, before moving onto the Lavender Line. June 2008 saw it return to Quainton. During 2009 vacuum brake equipment was again refitted enabling light passenger trains to be worked. Isebrook spent the summer of 2012 at the Chinnor & Princes Risborough Railway. A short visit was also made to the Didcot Railway Centre.

Isebrook started its 10-year overhaul early in 2013, being stripped down to the chassis for overhaul.

The remains of the locomotive were preserved at the Buckinghamshire Railway Centre at Quainton where it was restored and steamed again. It is owned by a Quainton Railway Society member.