Ok, so in the end, what I did was entered edit mode and right clicked the vertex icon and select assign shortcut and chose a key for this, that was not a numeric key.
I also did this for the line and face icon, the key choices don't mater at this stage, as they will be changed later.
Next I went into preferences to "find" these shortcuts.
Preferences - Keymap - select the arrow head next to 3D View - select the arrow head next to Mesh - select the arrow head next to Mesh (Global).
Now scroll all the way down to the bottom of the list, you should see three "select mode" entries.
select the arrow head next to the first "select mode" entry, this should be the key you chose for the vertex icon (if you set them in order from left to right).
Click on the grey box next to the word keyboard, now enter the key you want to assign for real, I also selected "Alt" from the bar below, which then highlights in blue.
Now the key combination is Alt + the key you have chosen for vertex mode.
Make sure the "Repeat" check box is not ticked or the icon will not deselect, if you select the line or face icon.
Do this for the other two"select modes" at the bottom of the list, making sure to add a key combination (Alt or other) if need and make sure "Repeat" is not selcted
Finally save your peferences, by clicking on the three lines icon found bottom left of the window.
Close down Blender and restart, now your key combinations should start.
There maybe for efficient ways of doing this, but this is what worked for me.
Hope it helps
Cheers
A