First of all, based on the wording of EU Reg. 261/04 you are not entitled to compensation for delay. Compensation is due for denied boarding and cancellations only. For delays you are entitled to care (food, hotel, phone call if needed).

http://eur-lex.europa.eu/LexUriServ/...01:0007:en:PDF

As you will note there is no reference to the compensation rules (art. 7) in art. 6 which deals with delay (cfr. art 5 on cancellations) = no compensation for delays.

HOWEVER, some EU case law decisions have applied a more 'generous' approach to long/excessive delays (but clearly outside the wording of EU Reg. 261/04) and have granted compensation for long delays. The arguments are that longer delays are quite similar to cancellations and have the same effect.

There is no clear answer for a delay of 4 hours for a long haul flight, but I doubt you would be entitled to any compensation under EU reg. 261/04 based on the case law above and the compensation appears to have been granted ex gratia by TG = you should be more than happy to receive EUR 300/pax