Hi Mel,
Sorry for getting your name wrong, I can tell you that John and Rachael had two children John (1875 - 1927) and Alice Gumble (1877 - 1949). Sadly Racheal died in the January of 1888 in Lambeth and John went on to marry Ada Boswell in the July of 1888. I have just noticed that the eldest child from John's second marriage was born in 1886, so I know that he was clearly faithful to Racheal. This now opens up a mystery for me, which means I will need to order a death certificate for Racheal, as for his father James it would not surprise me he was involved in an inquest. On the 6th of July 1863, there was a warrant for his in the police gazette with a description of him, hopefully, you can see that clip below.
Do you have an ancestry account if so I can share my tree with you, but pm me if you do with your username and I will send the request. I think from seeing your comments before you have some trouble with surnames, this maybe something to take into account. Gypsies never used surnames until they arrived in the UK, so if asked they would have no idea what to give in most cases they would make it up especially if they couldn't read or write. In the case of Gumble, it is German in origin and spelt Gumbel. My AncestryDNA supports this and I have some photos of family that came from the Austrian - Hungarian borders just after 1901 before moving to America via Liverpool.