Is it official now that the UK is not Europe????
Well, here what the web offers:
Eurocontrol, watch the weight mentioned, you are also
medium.
UK CAA it says:
9.6.1 Wake turbulence separation minima on departure shall be applied by measuring airborne times between successive aircraft. Take-off clearance may be issued with
an allowance for the anticipated take-off run on the runway; however, the airborne time interval shall reflect a difference of at least the required time separation.
Means that the allowance part was used; 40 seconds + 5 seconds for you to react and grabbing the microphone + 10 seconds for radio call and lights + 25 seconds for your own line-up + 40 seconds for your own take-off run that equals 2 minutes, the bare minimum. If you move slowly into position and delay by 10 seconds or 15, you will get even more separation...
Wikipedia
Take-off separation is purely based on timings. Separation based on distance is used for approach and landing...