The charity TAMBA (Twins and Multiple Births Association) has an article in its newsletter Multiple Matters, highlighting a question Caroline Pidgeon asked the Mayor on behalf of parents of twins:
Caroline Pidgeon:What instructions are bus drivers given about permitting buggies for twins to be taken on board London buses and for them to use the space for wheelchairs – as it is reported that many drivers are refusing to take such buggies until they are folded?
The Mayor:TfL advises drivers that passengers with double buggies can board by the centre doors, as it is too difficult for them to get on at the front. Passengers must ask the drivers permission first and show their ticket/pass or touch their Oyster card on the reader. Single buggies must board by the front door only. There may be occasions when it is necessary for a driver to ask a passenger with a buggy to fold it – for example if the bay is already occupied by another buggy or is required by a wheelchair user. Please forward any reports of drivers not allowing double buggies on board to TfL.
You can read the full article here.