Some parking meters in Hammersmith and Fulham are still not accepting the new £1 coins - 10 months after they were introduced.
MP Greg Hands highlighted the issue in a tweet with fellow Conservative and former London Mayor Boris Johnson, accusing the Labour-run council of "serial incompetence".
According to a sign on one of the parking meters, motorists are asked to use old round £1 coins, despite these being ceasing to be legal tender on October 15 last year.
The new 12-sided coin entered circulation in March 2017.
News in Fulham
The Labour-run administration say it is moving towards a cashless payment system, but that machines in the busiest centres in the borough have always accepted the new £1 coin and will continue doing so.
Chelsea and Fulham MP Mr Hands was photographed with Uxbridge and South Ruislip MP and Foreign Secretary Mr Johnson at a parking meter in Winchendon Road, Parsons Green.
Posting a tweet on Monday morning (January 22), Mr Hands wrote: "Great to have @BorisJohnson joining me in exposing staggering H&F Council serial incompetence - parking meters still don’t take the “new” £1 coin, almost a year since it came in."
In the image Mr Johnson appears to be feeding money into a the meter.
Another image in the same tweet shows a message from the council to motorists.
It reads: "Important Notice. This machine does not accept the new £1 coins.
"Please use old coins or pay for your parking by phone using RingGo. Further details can be found on the side of this machine.
"We apologise for any inconvenience.
"New ticket machines that accept the new £1 coins will be installed across H&F later this year."
Mr Hands later added: "This is serial incompetence from the Labour council.
"The new £1 coin was announced in the March budget in 2014. They have had four years to prepare for this, and have botched it badly.
"Boris was similarly shocked at the incompetence and was worried about customers losing their new £1 coins in the old machines.
"The old £1 coin ceased to be legal tender in October and still the council won’t accept the so-called 'new' one. This is incompetence added to incompetence.
"The council says that most customers now pay online, but thousands don’t, particularly the elderly and occasional visitors."
A spokesman for the local authority responded: “85% of all parking payments in H&F are now made via our phone app. Our new parking machines take card and contactless payments and the few remaining machines taking the old £1 coin will be replaced.”
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