Not a lot to go on David, but I'll put my mony on a robinia tree, only yesterday I noticed how bright yellow the foliage had turned.
It is sometimes known as False Acacia or robinia psudocacia. There is a popular garden variety with the variety name 'Frisia, which has golden leaves that turn even more brilliant in the autumn.
Ethel, it is definitely not a lime, different type of leaves.
Thanks for answering.
Thunderbird. I shall agree with you as the leaves are off the right shape. I know I did not supply a lot of info, this was due to the fact that I saw them from fast moving transport.