This unusual item turned up on eBay this month, being auction for charity.
The discarded sign was rescued by Tristan Peatfield, who worked as Stand-by Art Director and then Production Designer on that series (between the departure of Ed Thomas and the arrival of Michael Pickwoad).
The Isabella Peatfield fund raises money to support children's projects in Sri Lanka, where Isabella died. http://www.isabellapeatfield.com/
Questions and answers about this item
Q: I would like to know if there will be a Certificate of Authenticity (COA) or some other documentation illustrating the authenticity and history of the "DOCTOR WHO GENUINE ON-SCREEN USED TARDIS SIGN SERIES 5 (MATT SMITH) included with the item? Thank you.
A: I can arrange for this if needed.
Q: Hello, I was curious, do you know what episodes, specifically, this sign was seen in or could have been seen in? I understand it was Series 5, Matt Smith's first season, and with the range of assistants you listed it could have been anything before the Christmas special, but I was wondering if you could help me narrow that down. If not, that is perfectly fine. It's a wonderful item either way, but I was considering bidding on it as a gift for someone and it would be better if I could at least give an episode, a range of episodes, or say "this is the sign from most of Series 5" if that is indeed the case. Thank you.
A: Hi, I have asked Tristan this very question, but I'm afraid he just doesn't remember. It will have been earlier rather than later in Series 5, I believe.