Passport Change of Surname to HCI London by post

Hi,

I hold an India passport.
I want to apply for change of surname post marriage to HCI London office through post. On their website, it mentions that attested copies of spouse passport is required. When I emailed them regarding whether I can send it by post, they sent this back :

"Original marriage certificate with a photocopy and Self attested photocopies of Passports of his/her spouse along with spouse original passport. (original spouse passport- even if sent by post- to be shown at the time of submission the application) ".

Does this mean I have to send the original passport of my spouse as well in the post?

Have any of you used the postal service? Is it safe to do so or are they capable of losing my passport?

Thanks in advance.