A competition to design a viaduct carrying HS2 through south Bucks should be held, a Parliamentary committee has been told.

Planning consultant Jerry Unsworth told the HS2 Select Committee yesterday firms from around the world should be invited to design a bridge that would help protect the environment in the Colne Valley.

He said the competition would "stimulate creativity and innovation" and "gives a wide range of ideas and choices" of how to best protect the Colne Valley.

It's currently proposed that HS2 would cross the Colne Valley on a viaduct 3.4km in length - making it the longest in Britain - before going into a tunnel near Chalfont St Peter.

Mr Unsworth, who was representing South Bucks District Council at the hearing, said residents would prefer to see a longer tunnel rather than a bridge or viaduct however.

Mr Unsworth, the former head of planning and sustainability at Wycombe District Council, told the committee: "A simple design competition is what we consider is required in this situation - we think that's a mechanism to respond to the sensitivity to the Colne Valley, and would enhance the locality.

"It's justified by the sheer scale of the structure. There are compelling reasons to require excellence in design, and design that, as far as we can, enhances the area."

He added: "It's worth reiterating the district council support the principle of a tunnel - if we agree to that, this competition wouldn't be required.

"We do think more needs to be done to achieve a structure we can be proud of."

The tilting Millennium Bridge in Gateshead is an example of a structure built after an international design competition, he added.