The reasons given for the lack of popularity of the acorn design of valve are both the difficulty of manufacture in the UK and the ease with which the insertion of the valve into the socket could crack the glass envelope. Stef Niewiadomski in his article Acorn Antiques captions the image above with the fact that he has not dared to insert the valve into the holder. Such is the strength of feeling on the difficulty of using these valves.
The above image shows an alternative to redesigning the acorn 954 into the 9001 on a B7G base. Quite simply it is a zero insertion force valve socket. Loosen the two screws and the top ring rotates to place the holes above the contacts in the ring below. Rotate the top ring and secure the screws and the upper ring then holds the pins tight against the spring contacts. Brilliant!
The part number APW835.