2 SSD's and 2 Operating Systems.

[Kronos]

have just installed Windows 10,(Oh what fun that was) on a brand new SSD with the view to keep my Windows 7 SSD intact.
I was hoping that once I reconnected all HDDS that on boot I would be given the choice whether to boot to 10 or 7 but it booted straight to ten. I could have course just keep disconnecting and reconnecting the SSD's dependent on what I wanted to do but i was hoping for a simpler solution. Is there one?

I am hoping for confirmation that a solution offered elsewhere is the way to go.

This involves opening the CMD with admin and typing:
diskpart
list vol
sel vol 4
assign letter=S
exit
bcdboot E:\windows /s s: /d /addlast
diskpart
sel vol s
remove
exit
exit

Using info from here with e being the drive that Windows 7 is on.

 

[Kronos]

The above commands did not work as when I booted or rather tried to boot into Windows 7 I received this message. Not sure what to do to resolve this and try and as for using the F8 key to select boot. I did not think of that. I tell you this getting on in years coupled with a medical condition don't half kick the bejeezers out of one's cognitive abilities.
Can I sort the dual boot issue out or have I buggered it?

 

[Kronos]

It was secure boot and by changing a setting to any OS sorted it. Thanks all.