Mr Speechley is accused of trying to influence the route taken by a new bypass in order to increase the value of a field near his home village, Crowland. He denies the charge.
The trial heard that original designs placed the bypass close to the existing A1073 road. However, Mr Speechley told officers he wanted the bypass to be built further away from the village.
That would put his field between the bypass and Crowland, a prime position for future development, the court heard.
It is also part of the prosecution's case that Mr Speechley failed to properly declare the land in the register of councillors' interests.
The prosecution's first witness, Lincolnshire's former director of environmental services Paul Kirby, accused Mr Speechley of being 'crass, intimidating, nasty - a tin-pot dictator'.
Mr Speechley's barrister William Harbage QC, asked Mr Kirby: 'He's not a shrinking violet by any means is he?'
The witness, now director of reform strategy at the Cabinet Office, replied:
'It has been well documented that he would go a lot further. He could be crass, intimidating, nasty - a tin-pot dictator.'
The barrister said: 'He attempted to get things done.'
Mr Kirby replied: 'Regardless of the law or the circumstances at the time.'
The leader 'passionately' campaigned for a new bypass to be built, when colleagues viewed the scheme as his 'parochial pet project', Mr Kirby added. Under cross-examination he confirmed that later studies by officers identified the A1073 project as an important one. The trial is expected to last six weeks.