I agree with many of the sentiments expressed here about how boring a Sunday could be under the control of the god botherers. However, they were not completely wrong as these days there is no special day of the week for families to get together - frightening as that may seem to some. The day appears to have been given over to more retail therapy, indeed the big shops are looking to drive back the minimal Sunday trading protection so that people can do even more shopping...crazy!! There's a balance to be struck but we should make (common) time for families.
UBT I have to disagree to a level with this as I see a surprising amount of families, single, multiple and extended out and about enjoying a walk and time together then on for lunch somewhere or for a late afternoon/evening bite to eat.
Visit any of the big parks or open spaces in and around London and they are awash with families enjoying to fresh air and I suspect that this is a reflection of lots of the mums and dads being stuck in offices and welcoming some time outside with the children etc.