Spooks 5 contain hoh-subtitles (I own it). BBc-shop has informed me that all BBC-dvds marked bbcdvd, 2edvd or cctv have hoh. So if you look at product details and find either of above there would be hoh-subtitles.
You have to go to: www.bbc.com. Then you write a title in search and click product info. BBC told me about these codes/markings 2 years ago and I've made use of them since, and they've always been correct. Now today when I checked, it seems they've changed their coding (guess I'll have to inquire again). But I have Spooks 5 and it has hoh.
They tell me from BBC-shop info. that code klt means that a dvd does NOT have hoh subtitles. So that means that Spooks do not have hoh any more. I wonder why they changed, since it obviously isn't for the better for their customers. And bbc has just confirmed that Spooks 6 does NOT have hoh. You can also look for Spooks at "www:dvd-subtitles.com" and "www.dvd-earth.co.uk" to find subtitle info.
Hello Inventor. Just today I saw Spooks 6 in a shop in Denmark with subtitles SDH, which means subtitles for the deft and hard of hearing in English. If you search bar code: 5030305620523 on amazon.co.uk you get Spooks 6. Spooks 7, Bar code: 5030305620530, also SDH. Good luck.