According to this article the recent postal strikes have delayed around 30 million letters that's about 40% of a normal days post. The situation could become worse as further strikes are planned for next week and will go ahead on Thursday, Friday and Saturday unless an agreement is reached. Although Royal Mail hopes to clear the backlog of letters and parcels before further strike action takes place, customers should expect further delays to mail and during this time we regret that we are unable to guarantee any delivery times.