Will different tyre tread depths fail the MOTA?

As the title says, will different tread depths on the tyres on my Ford fiesta cause it to fail its MOT? The tread itself are all legal and in good condition the only thing is one tyre has a different tread type to the other 3, will this cause a fail? I have read different things online, some saying that it will be fine as long as the tread is in good condition but other sources saying its illegal, can anyone clear this up please.

So long as the tread depth is over 1.6mm on all tyres, no problem. Provided you don't mix cross ply and radial tyres on the same axle it's also fine.