The switch in the eBay auction is specific to Humber Sceptre and, functionally, will work with the late Alpine. However, the handle is longer and as mentioned earlier, the angle is different. More importantly, the mounting method is different as the Alpine has a switch body with a single notch that runs the length of the smaller diameter threads. The notch matches tabs in the openings of a pair of 'clamping plates' to keep the switch from rotating thru use and is secured with a chrome bezel similar to those for the dash switches. Once mounted onto the two plates the switch is sandwiched between the lower/upper halves of the column cover.
The Sceptre switch body threads are larger diameter than the Alpine with a flat spot running the length of the threads (similar to the ignition switch). The switch inserts into a metal bracket with a mating flat spot to keep the switch from rotating during use with a large hex nut similar to those used on radios of the period. Once mounted on the bracket it is bolted onto the steering column and the mounting bracket is shown in the auction pics. So, this Sceptre switch could be used with late Alpine but it's gonna take fabrication. BTW, there were several variations of this type switch used in the Humber Sceptre and Sunbeam Rapier.
There were far, far more overdrive Sceptres & Rapiers than Alpines.
Mark ..... volvoguys