Man arrested after home-made bomb thrown through window of Tory MP's constituency office Two explosions heard outside Tory Party building in Bourne, Lincolnshire Contains office of Planning Minister, Grantham and Stamford MP Nick Boles Mr Boles, who was not in office at time, said: 'I deplore this act of violence' He has sparked controversy over comments on immigration and planning The offices of an outspoken Tory minister have been targeted by a home-made explosive. Two small explosions were heard outside the Conservative Party headquarters in the small south Lincolnshire market town of Bourne between 12.20 and 1.30am today. A window was smashed by shrapnel from one of the devices and scorch marks were left on the pavement outside the building which is the constituency office for Grantham and Stamford MP Nick Boles. Lincolnshire Police said a 24-year-old man had been arrested and was helping police with their inquiries. But a spokesperson said early indications suggested the incident was not linked to any wider issues or recent events in the county. Probe: Police officers pictured entering the Grantham and Stamford Conservative Association office in Bourne, Lincolnshire, following an overnight explosion High-profile: The building is the constituency office for Grantham and Stamford MP Nick Boles One eyewitness who was woken by the second explosion said a firework with coins taped around it had been placed outside the office. Speaking this morning Mr Boles, who was not in the office at the time, said: 'Obviously, I deplore this act of violence. The incident is being investigated by the police and I know that everyone will do whatever they can to support the investigation. In the meantime, we should all carry on doing our jobs as normal. Investigation: Police tape surrounds the offices of Planning Minister Nick Boles in Bourne, Lincolnshire, after they were targeted by a home-made explosive in the early hours of this morning Damage: A window was smashed by shrapnel from one of the devices and scorch marks were left on the pavement outside the building He said he hoped to learn more about the incident 'in due course'. The coalition Planning Minister last month criticised immigration for helping to fuel rises in house prices that are preventing young people from owning their own home. Mr Boles told the Mail: "I have become much more critical of immigration. A very substantial contribution to housing need comes from the level of immigration in the past two decades. Targeted: Nick Boles has recently made controversial comments about immigration and planning Earlier this year, he admitted he is "nervous" about the impact of an influx of Romanians and Bulgarians who will have a "right to a home" in Britain. Mr Boles also recently caused fury among environmental protestors by stating building houses will create more 'human happiness' than preserving fields. Mr Boles said the Government is determined to speed up the rate of house building despite opposition from country groups. Oxford-educated Mr Boles was tipped as a potential London Mayoral candidate before being diagnosed with Hodgkins Lymphoma, a type of cancer, in 2005. He attended last year's elite and secretive Bilderberg Conference in Virginia and this year's gathering in Hertfordshire has been the scene of anti-capitalist demonstrators. Locals reported hearing two small explosions between midnight and 1.30am. The building which is home to the Grantham and Stamford Conservative Association was this morning taped off with four police vehicles outside. Scorch marks could clearly been seen on the pavement. One resident said: 'The first explosion was around 12.20am and then I heard the second one at around 1.30am. 'A firework with two pence and one pence coins wrapped around it had been left outside a hall next to the Conservative's office. When the firework went off the shrapnel broke the window. Martin Hill who is the local leader of Lincolnshire County Council came out because he had a key, and the police and fire bridge were here really quick. Outspoken: Mr Boles, who was not in the office at the time, said he was waiting for an update from police A bang and the sound of breaking glass were heard at the junction of North Street and Burghley Street in Bourne. A spokesman for Lincolnshire Police confirmed there were no reports of any injuries and only minor damage had been caused. Caroline Glithero, who lives nearby, said she heard two explosions about 45 minutes apart. 'I heard two very loud bangs and on the second one I went to see what it was and found a lot of debris and a window broken,' she said.