Do not trust the use by dates on these packs
The chicken itself is generally very good for the price but the use by dates on the packs are way out. I opened one that was still three days short of use by and it was off - grey and smelly. What I do now is freeze the packs immediately they're delivered and de-frost them as required. I suspect the problem is this is not fresh chicken but frozen packs that are being de-frosted by the supplier before delivery to Tesco.