Birchwood Guest House 

The Birchwood Guest House has the most amazing front garden you're likely to see throughout Portsmouth. Beautiful and lovingly tended, it welcomes you into the equally well-tended establishment. The rooms are carefully thought out and decorated (rather than just thrown together with old Holiday Inn stuff), the beds are comfy, and everything is scrupulously clean. The hosts are kind but refrain from swarming all over you. If you need a taxi, they will call one; however, they do not insist on forcing their advice upon you. Fine English breakfast is provided, without any more commentary than "Did you sleep well?" or "Looks like a lovely day." I liked their sense of English reserve combined with their willingness to provide help when needed.
The Birchwood is within easy walking distance of a variety of pubs, restaurants, shops, etc. Actually, we walked everywhere in Portsmouth (bring comfortable shoes!), and this guest house, located directly across a small park, made a fine retreat at the end of the day. So much nicer than large, tasteless hotels!