Ymatebodd Carillion yn ffurfiol gan roi sicrwydd ynghylch ei sefydlogrwydd, ac oherwydd  hyn, ynghyd â'r ffaith mai contract i ddylunio yn unig oedd Llywodraeth Cymru wedi'i ddyfarnu ar y pryd, ni allai'r Llywodraeth dynnu'r contract yn ôl yn gyfreithlon. Byddai peidio â dyfarnu'r contract i Carillion wedi golygu y gallai Llywodraeth Cymru gael ei herio o dan gyfraith gaffael.
Carillion formally responded giving assurances as to their stability, and this coupled with the fact that they were only being awarded a contract for design at this stage meant that the Welsh Government, on balance, could not legitimately withhold awarding the contract to Carillion. Not awarding the contract to Carillion would have opened the Welsh Government up to potential challenge under procurement law.