A discussion around the Lee-Enfield No.4 rifle in Service Rifle (b) configuration, centre bedded by Alfred J Parker of Birmingham. An earlier extra vid of this rifle being shot is here: https://www.youtube.com/watch?v=2NaeIkGrkLE
SR(b) was the forerunner of British/Commonwealth Target Rifle, fired with the .303 British and Commonwealth service rifles of the day. Externally, aside from a mid sling swivel and target sights, they're standard. However, various internal perfections were permitted, after experiments running from late 1952 to early 1953 with various alternative methods of stocking-up. Centre bedding had been applied in India to refurbished No.4 rifles, and it was trialled, leading to its adoption for NRA competitions at Bisley and elsewhere, although the British army didn't adopt it itself.
Canadian maintenance manual: https://drive.google.com/file/d/1YjHVdfuHz8fNTGIhpSZPcyF6QFlepbZD/view?usp=sharing