Hello,

1. I hold an Indian passport (need visa to enter UK)
2. I have a Swiss B Permit (valid for a year)

I understand that this permit allows me to travel in Schengen area without my passport.
I also realize that UK is not a part of Schengen.

My question is if I travel to London by rail/air, is the Swiss B permit sufficient as an identity / a travel document to enter UK or not?

Thanking in anticipation

Nope, you need a visa through World Bridge, Geneva or Zürich

Indian passport holder UK transit Visa

No, you will need to show your passport when you depart Switzerland and enter the UK.

And with the new system at Zurich's Kloten airport passports to non-Shengen destinations are give a thorough scrute by the Swiss border officers and a second time at the departure gate before boarding...

Three options:
......get to Calais and find the crawl-space in a truck
......bump into Doctor Who and ride the Tardis
......get a UK tourist visa

Basically, you'll not make it onto any passenger transport which has a next stop in the UK.

Definitely need one but should not be a major problem - you might even get it for 6 or 12 months allowing you to travel there frequently.