Gregory is a member of the Parliamentary Bar Mess and undertakes work not only in relation to major infrastructure bills but in all aspects of Parliamentary work. His appearances before Parliamentary committees and advisory work include:
- Three Rivers Council Petition in respect of HSC Bill (2015 on going).
- EMI Petition in respect of the Crossrail Bill regarding the dislocation and noise arrangements in connection with EMI music studios in Soho.
- City Post AMP Limited Petition in respect of Crossrail Bill. Appeared of Petitioner and established ability of Petitioners to recover costs in hybrid bills.
- Orange and Vodaphone Petitions in respect of the London Local Authorities Bill (2007) in connection with proposed creation of criminal offence for telecommunications operators.
- Imperial Tobacco Limited Petitions in respect of the London Local Authorities regarding the London (prohibition of Smoking in Places of Work) Bill (2004/05) and Liverpool City Council (prohibition of smoking in places of Work) Bill (2004/05).
- Written representations on the scope of the "statutory authority defence" in the Planning Bill (2007).
- Promoted the Cambridgeshire Guided Bus Transport and Works Order (longest guided bus in Europe) (2004). http://webarchive.nationalarchives.gov.uk/+/http://www.dft.gov.uk/pgr/twa/ir/cambridgeshireguidedbuswayin5647