James Spelman continued his outstanding Festival with another big century to help Norfolk establish a first innings advantage of 26 on a stormy day at Horsford.

The Great Witchingham opener, who made a career-best Minor Counties Championship score of 181 against Northumberland last week, carried his form into the second match against Buckinghamshire.

Having reached his 50 on Sunday night as Norfolk responded to Bucks' 312 all out by reaching 106-1, Spelman carried on regardless to make 149 in their 338 for six declared.

Bucks responded positively, finishing the extended day's play on 141-1, suggesting – with two quality batsmen well set and more to come – thatthey have every intention of setting up another exciting Horsford finish if the weather allows today.

Eighty minutes of play were lost yesterday, a shower interrupting the Norfolk innings before a brooding sky with flashes of lightning and rumbles of thunder, prompted the end of it – home skipper Chris Brown declaring three overs from the end of the 90 following an early tea.

By then Spelman had taken this year's overall Festival century count to four in five days – with four days still to play. His eighth championship century was highlighted by a six he hit off Simon Stanway into the hospitality tents – leaving Norfolk's statistical fraternity scratching their heads to recall if there had been any other maximums in his 108 previous innings.

He was eventually bowled, fourth wicket down, to spinner Shaftab Khalid after facing 241 balls in 287 minutes, having helped Norfolk to 303 for four. In the process he had extracted a measure of revenge against Khalid, who on Saturday took four for 16 as Burwell skittled Witchingham for 79 in the EAPL. Yesterday Khalid finished with figures of two for 124 from 32 overs.

Spelman played his part in four significant partnerships. Following the first day's opening stand of 59 with Ben France he put on 77 with Trevor Ward (39) for the second,101, in 115 minutes, with Peter Lambert (54) for the third and 67 with Luke Caswell (51) for the fourth.

Lambert's score equalled his previous championship best while Caswell's came at better than a run-a-ball. That made it the most entertaining knock on a day of generally laboured progress – but Norfolk's application and discipline gave them the lead they wanted.

Not that it lasted for long. The young Bucks openers swiftly wiping it out in a first innings stand of 74 before France trapped Hamza Taj for 26. His 19-year-old partner Shaan Khan, following up his first innings 74, went on to reach 81 not out, his 50 coming off 49 balls and including nine boundaries, while former Northants star Rob White was unbeaten on 30 at the 7.30pm close.

To further make up for yesterday's lost time today's action will start half an hour earlier at 10.30am.

Norfolk v Buckinghamshire (day 2)

Overnight: Bucks 312 (Shaan Khan 74, R White 59, C Brown 5-74), Norfolk 102-1 (JM Spelman 54no).

Norfolk 1st innings continued

JM Spelman b Khalid 149

TR Ward c Helm b Khalid 39

PA Lambert lbw b King 54

LW Caswell c & b Stanway 51

CJ Taylor lbw b Stanway 4

RJ Findlay not out 5

C Brown not out 1

Did not bat: JS Blake, MP Eccles, KJ Bunting

Extras lb4 nb 10 14

Total (6 wkts dec, 87 overs) 338

Fall: 1-59 2-136 3-237 4-303 5-314 6-337

Bowling: King 12-2-61-2, Helm 5-2-29-0, Khalid 32-2-124-2, Stanway 32-6-94-2, White 4-0-15-0, Payne 2-0-11-0.

Buckinghamshire 2nd innings

Shaan Khan not out 81

Hamza Taj lbw b France 26

RA White not out 30

Extras nb2 w2 4

Total (1 wkt, 37 overs) 141

Fall: 1-74

Bowling: Eccles 3-0-22-0, Bunting 8-0-39-0, BJ France 6-0-24-0, Brown 7-0-23-0, Findlay 5-0-11-0, Taylor 4-0-16-0, Lambert 1-05-0.

Today: 10.30am start