Yes and no.
There is this whole thing that people think getting lots of searches on their credit report affect their ability to take out finance, its really very marginal, and would be factored in a bit more when it comes to loans, credit cards etc, unsecured finance where system based scoring is more heavily involved, even then it's marginal. If it came down this, you would have had to have been literally on the edge anyway.
When it comes to mortgages its a bit different, mortgage lenders don't lend based on your "credit score" or at least not those rubbish numbers that the likes of Experian or Equifax provide you.
Most lenders will have their own internal scoring systems based on a whole ton of data (some older lenders dont even do this, Family building society/NCBS and Cambridge Building Society its all manual for example) but the score is based on a whole ton of metrix, statistical based informaiton (eg X person, of X age, in X postcode, in X income bracket with X amount of kids etc etc etc etc the list goes on) based on however many thousands or 10 of thousands of mortgages written performed or didnt, and what percentages etc. These are constantly adjusted depending in the lenders risk appetite at any given time.
Obviously your personal credit search (note not score, dont get these confused) is factored in, and any adverse credit information will be checked against a lenders criteria, and unsecured debts factored into affordability, and for most lenders the systems will do this automatically at the initial stage (not all) and almost always be checked by a human prior to offer if it gets that far.
When it comes to previous searches, unless it was an extreme amount, these generally would not affect anything. Where it might be asked if there were several searches from other mortgage lenders prior to the application, because then the question may be asked, why were these searches done and no mortgage taken out, were they declined, and for what reason, is there something we are not being told? And even then likely be perfectly fine reasons for that.
It would have to be a pretty extreme amount to start affecting anything, yes I mean, in your example given, that would end up being a concern, I think most people would struggle to take out 100k of credit cards in a short space of time, but yes, I mean, if you somehow managed to do that, and then also, if the application was checked post offer (and as previously written, would have to be some extenuating circumstances or material change for this to even happen in the first place) then yes it could affect your mortgage offer.
