In the middle of Edgeware Road, just north of the junction with Bayswater Road, there is a traffic island. This was the site of the Tyburn Tree, the place of execution of many of our English Catholic martyrs. The site used to be marked by the small memorial pictured above. Unfortunately, the traffic island has recently been refashioned and the memorial is no longer there. This is a pity because I know that many Catholics used to like to venerate the cross, even from the opposite pavement (it is a busy road and the island is fenced off.)
My guess is that this is merely an oversight and that the planners did not realise the significance of the cross. It would not cost much to place a small memorial on the site of the Tyburn Tree similar to the one that has been lost.
The traffic island is on the boundary of two wards of Westminster Council, Bryanston and Dorset Square and Hyde Park. The links take you to the pages for those wards with information about the ward councillors and email links. A few polite emails to the relevant councillors might be a start to arranging for a simple memorial being restored to this site which is of such significant historical and devotional interest.