Andrew made the pledge on the Royal British Legion's campaign website, www.timetodoyourbit.org.uk.
The website also features the charity's general election manifesto, which sets out priorities for the next government to improve conditions for service personnel and their families, the bereaved, veterans and dependants.
Kevin Shinkwin, the Legion's head of public affairs, said:
We're really grateful to Andrew for pledging to do his bit. The entire armed forces family needs the support of politicians from all parties, and our manifesto outlines practical ways the next government can help. We hope all the parties will give it serious consideration and that every prospective parliamentary candidate will pledge to do their bit.
Andrew said:
I was delighted to support the Royal British Legion. They have an important role to play in highlighting the needs of the whole armed forces family. I have pledged to do my bit and would encourage everyone to visit the website www.timetodoyourbit.org.uk to find out how they can get involved in the campaign.