pitching a wort for ESB onto WYeast 1028 London yeast cake

I am getting ready to bottle a pale ale that was made with WYeast 1028 London liquid yeast. Once I rack the pale ale out of the carboy I would like to use the yeast settled in the bottom of the carboy for another batch of beer. I want to start an ESB. My question is (1) should I wash the yeast first and decant into pint size mason jars and then make a starter for the ESB, or (2) can I simply pitch the cooled ESB wort right into the carboy with all the yeast from the pale ale sitting in the bottom. Would this be too much yeast for an ESB?

Also anyone passionately opposed to using WYeast 1028 for an ESB? I would rather not have to buy another yeast if I can simply use this one again...

There is no need to wash it, but I would recommend you only use part of the cake.

When you have bottled the Pale Ale, pour about a quart of sanitized water into the fermenter (tap water may be fine, if your tap water is OK and you will be re-using it in a couple of days, otherwise use bottled or boiled and cooled water), swirl it up and pour it into sanitized mason jars. Keep in fridge until ready to use. It will easily keep this way for a month, but you may have to periodically relieve the pressure in the jar.

If used within a month, no starter is needed. Pitch about 1/4 of the cake.

If you have too much yeast to start with, it doesn't reproduce. During the reproduction phase, a lot of the flavors are created, so if you pitch way too much, you don't get many esters from the yeast.

I don't see any reason to not use 1028 for the next brew... Its flocculation is a bit lower than I would go for, but given enough time, it will clear up nicely... I do think its profile needs to be in line with what you're after though (as with all yeast)...

"A rich, minerally profile that is bold and crisp with some fruitiness. Often used for higher gravity ales and when a high level of attenuation is desired."

As already mentioned, use part of the cake... You could take the yeast cake out of the carboy, let the trub settle out, and then pour the good stuff into a few cup/pint mason jars and reserve them in the fridge. Once settled out more, it will be easier to pitch into the next brew... Plus, you'll have more yeast to use in future brews...

If you go past a month (or so) before using, just make a small starter to make sure the yeast is still ready to rock and roll. Do that 24-48 hours before you plan to pitch it and you'll be fine... Worst case, you'll discover the yeast isn't working anymore, and you'll have time to get fresh yeast...