Upvote:17
Normally, it's fine to travel with a visa in an expired passport, but this situation arises when a visa is issued in a passport which was valid at the time. The fact that the vignette has the wrong passport number indicates this is a mistake.
If you make it to the UK border, the border officer would almost certainly be able to work this all out. Once you enter the UK, you will collect your biometric residence permit, so the entry vignette will become irrelevant. However, if this mistake is noticed by your airline before departure, they may not allow you to fly. Also, despite the existence of the biometric residence permit, some people (employers, airlines, banks) may wrongly insist on seeing the vignette, so this problem could follow you around for a while.
You will probably know that the Home Office charge exorbitant fees for attempts to contact them about visa applications. However, I believe that in your case, you can follow the instructions here to contact UKVI International Sheffield by email to have your vignette correctly issued. Since this would involve sending off your passport again, this could take several weeks. If you are traveling very soon with no opportunity to correct this, I would chance it. Just hand over the two passports to the staff member who checks your documents without any indication that you think anything is wrong. You are extremely unlikely to be turned away if you reach the UK. But if there is time, you should try to have this corrected.