A new badge specially designed to make travelling easier for people who find it difficult to stand has been launched by Transport for London (TfL) on Friday 28 April.
The "Please Offer Me a Seat" badge is available to disabled passengers and those with hidden conditions, illnesses and injuries, to help them find a seat on public transport.
"These blue badges will make a real difference to passengers who need a seat but just haven't felt confident enough to ask for one," said Sadiq Khan, the Mayor of London.
"I've no doubt they'll soon become as recognisable across the capital as our popular Baby on Board badges."
The badges were created following requests from customers who can struggle to get a seat as their need is not immediately obvious. The network-wide roll-out follows a six week trial with 1,200 people last autumn.
The research found that more than 72% of journeys were found to be easier as a result of the badge, and 98% of people taking part in the trial said they would recommend it to somebody who needed it.
Olivia Belle, director of external affairs at Arthritis Research UK, said: "There are over 750,000 people in London living with hip or knee arthritis alone. The daily pain and fatigue caused by their condition can make everyday tasks, such as standing on a train, extremely difficult.
"However, the pain is invisible and its severity can fluctuate on a daily basis, which can make it really difficult to explain and to see.
"We're really supportive of this new scheme, and hope it will make Londoners understand the impact of invisible conditions like arthritis and make getting a seat when needed easier."