transfers from Heathrow to Center City

The only thing I have noticed on Sunday is less frequency. But have not made the run from the airport on Sunday but would assume fairly normal service.

I took the tube from the city to Heathrow on a Sunday morning once and had no issues. As was mentioned above, the services may be less frequent; but since Heathrow is so large, you'll have excellent connections (with little waiting) any time.

Engineering works on the Underground lines, when needed, are often scheduled for weekends. That would be the only complication I can think of.

Bus service should not be an issue on a Sunday. You can take a National Express coach directly from Heathrow to Victoria coach station.

Adding to Tim's comment, you can check on planned engineering works on the transport for London website (www.tfl.gov.uk). If you go to the tab "Live Travel News", you can see the planned station and track closures for the next 6 months. I'd also suggest that you check the schedule for your date of travel a day or two before you depart.

Thank you all so much for your help and setting my mind at ease.