From what I'm aware all over the UK, 66 kV and 33 kV are both at 11o'clock, therefore to transform from 66 to 33 kV, one requires Yy0. I have been involved in the installation of such a transformer in the North East of England. This was a Yyn0, with an impedance earthed LV neutral to limit earth fault current on the 33 kV network. No HV earth was supplied as it's normal to only earth at the source end on networks below 132 kV.
As someone else has stated, as 132 and 11 kV are typically both at 12 o'clock in the UK network (referenced to the 400/132kV Grid system), these also require a Yy0 transformer. At this voltage I'm guessing that this would be a YNyn0 typically in the UK, as it is standard practice to earth 132 kV at source and line end, and it is typical to earth the 11 kV system at the main supply transformer point. 132 kV is typically solidly earthed to ensure no damaging voltages develop at the HV winding neutral point during an earth fault. At 132 kV and above, HV windings tend to have graded insulation for reasons of economy, so elevating the neutral voltage too high above earth may overly stress the lowly rated insulation close to the star point of the windings.
I've never done a 132 / 11 kV sub, but I would guess that earthing is quite interesting due to having to get a low enough impedance on the site to limit any potential rise between HV and LV earths that would allow dangerous step potentials to develop. Most DNO's have very strict earth impedance requirements before allowing connection of HV and LV earth systems for this reason.
Useful references on the topic include the J&P transformer book, but most DNOs publish freely available information on what phase relationship and vector groups to consider when connecting at different voltage levels on a network. See a link to Eon's below: Relevant info is on page 89
Eon Primary network design manual
This of course differs from country to country. I'm currently working in a location where the entire grid runs at 12 o'clock with solidly earthed neutrals throughout which is quite strange.