The Last Post from Windsor (Mail) If you are really anxious to get a letter in the post tonight, there is a late collection at 7.30pm weekdays from the pillar box opposite Princess Christian's Hospital at the eastern end of Clarence Road. We have used the 'last post' opportunity on a number of occasions and whilst we cannot offer you a guarantee of next day delivery for First Class mail, our own letters often arrive in London, and elsewhere, the next morning. A Sunday collection is made from Bexley Street Pillar Box at midday. Local Information Royal Windsor Home Page To contact us, email Thamesweb.