I wonder is there an easy way to see how BA logged the flight status: it was flight BA8491 LCY TXL on 19DEC2018 - what are the best tools to check?

EDIT: checked EUClaim and they siad no claim was possible.

These are the figs direct from BA:

Flight BA8491 from LCY to TXL.
Scheduled departure date and time: 19 December 2018 08:20 GMT
Actual departure date and time: 19 December 2018 11:18 GMT
Scheduled arrival date and time: 19 December 2018 10:00 GMT
Actual arrival date and time: 19 December 2018 13:00 GMT
Total delay: 180 minutes

and text 'can confirm your flight, BA8491, at 08:20(GMT) was delayed for 178 minutes before take off.' 'your claim for compensation under EU Regulation 261/2004 has been refused.'

Bottononline suggests it might be possible, but want me to commit.

Is the delay calculated on arrival time, or flight departure delay?

Any other tools to check?