Minority ethnicicty has little to do with it, you can apply the same principles to anyone, i.e, a red haired person,some one in a wheelchair , someone from Wiltshire etc.etc.etc..
Whoever it is has to convince their local party officials to allow them to stand for parliament which could take years. Then their party has to be elected with a majority, it will then take several years for that person to impress the other members enough to be elected leader. If they are not the party in power it will take many more years.
Everyone who seeks power by election faces an uphill struggle and colour does not enter into it.