I have booked a reward fight on CX 289 from HKG to FRA, the arrival time is 0635 am, then I booked a separate BA 901 ticket from FRA to LHR, the BA departure time is 0730.

I am sure I can have my checked bags sent straight to LHR, but will I be given the BA boarding pass in HKG?

If the CX flight has been delayed, will BA book me to other subsequent flights on the day or?

Thanks!

Too short if your delayed and BA would not be obligated to provide onward travel as its separate tickets.

Isn't the MCT 1 hr? Am I reading it correctly?

I don't think you can interline - you're under MCT. If hand baggage only you can try and run for it with a BA online BP but with bags this isn't going to work.

Does that mean I can't even check my bag straight into London but need to get the onward BA boarding pass at FRA and re-check my baggage?

Thanks!

You might get the BP online.

But I would seriously think BA will refuse to retrieve your bags at FRA even if you approach the BA counter there.

According to this site, MCT at Frankfurt for international-to-international is 45 minutes. Which seems short. At the end of the day, if you want your luggage checked through, you will need to satisfy whatever MCT is in your originating carrier's system - so call CX and check what they think the MCT is. If it is any help, I have on one occasion had a connection, with luggage, which was less than the MCT (it may even have been through Frankfurt, but I don't recall), also on separate tickets, but the lovely F check-in staff at HKG (I am CX Diamond), after a minor flap, said they would override the system MCT restrictions and issue the luggage tag anyway, but were very clear in stating that the luggage might miss the connection and they were doing this at my own risk. Which was fine. Especially as it didn't miss, and arrived safely with me at my final destination (London).

If you aren't checking luggage, you can always get the second BP online. You should also try to link the PNRs (again, call CX) so they can try to protect the connection.