How do I release this line connection?

I have been trying in vain to release this fuel line from the FPR so I can attempt changing injector seals and washers. In videos I have seen a simple push against the connector seems to release it. I have tried pushing with a brake spanner against it without any joy. If I grab it with my fingers it does rotate a little. Any ideas?

It has tabs like the one pointed with red both sides, you have to squeeze it as to push them in then just pull the connection out, it might have a rubber dust cap which covers them

I can get a finger to the tab on one side, but it started to rain and I am in work till next weekend. Its never easy!