Sorry, I have no references to this.
Back in the late 50's I was shown a ~16th century drawing of Leagrave (the source of the river Lea) by the late Dr. J Dony who was my history tutor at the Luton Grammar school. This was an artist impression of Wauluds Bank and included standing stones marking an apparent "entrance".
However, there is no evidence of standing stones ever having been located at this site, and having spoken to James Dyer about it I believe the diagram was probably not accurate.
There were some Pudding Stone boundary markers around Luton, and at river crossing points, which have long since been destroyed.(The last being located on Market Hill until the "developers" threw it away!).
Something is not right. This message is just to keep things from messing up down the road